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  • Triticum aestivum  (276)
  • Drosophila  (237)
  • Springer  (513)
  • American Physical Society
  • MDPI Publishing
  • 1995-1999  (380)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 91 (1999), S. 403-412 
    ISSN: 1570-7458
    Keywords: aphid ; Diuraphis noxia ; Triticum aestivum ; endosymbiont ; insect-plant interactions ; phloem ; amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The feeding behavior of Diuraphis noxia Mordvilko (Homoptera: Aphididae) on susceptible hosts causes both ultrastructural and tissue level damage which may affect phloem composition. Genetic evidence suggests that endosymbiotic bacteria in most aphids overproduce limiting amino acids to benefit hosts but that D. noxia depends less on endosymbionts for these nutrients, possibly due to an enriched diet. To determine whether D. noxia feeding damage results in higher concentrations of essential amino acids, stylet exudates were analyzed from wheat (Triticum aestivum) damaged to different degrees. Comparison of samples from undamaged and damaged susceptible wheat revealed changes in amino acid composition and an increase in levels of essential amino acids, indicating a nutritionally enhanced ingesta. The changes in stylet exudates paralleled changes in leaf exudates, indicating that the effects are systemic. Feeding damage is not observed on a resistant wheat host, var. Halt, and leaf exudates from infested Halt did not show changes in amino acid composition. Mean relative growth of nymphs was significantly lower on Halt than on susceptible Arapahoe, indicating that Halt is a less suitable host. Both varieties show similar amino acid levels in non-infested samples, suggesting that D. noxia infestation does not enhance the phloem environment in Halt. This study provides evidence that aphid feeding can generate a nutritionally enhanced phloem diet.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 90 (1999), S. 175-181 
    ISSN: 1570-7458
    Keywords: Olfactory response ; Drosophila ; menthol ; bioassay ; trap assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A modification of the trap assay (Woodard et al., 1989) was used to evaluate the response of Drosophila melanogaster (Meigen) to food media containing menthol. Dose-response curves for flies to mentholic foods were produced for flies that had been pre-exposed to menthol, during development and adult life, and flies that had not been exposed to menthol before the assay. Mentholic food media were less attractive to Drosophila than plain food medium. Rearing flies on a medium containing menthol reduced their aversion to some concentrations of menthol. The rearing effect was not simply due to lowered general activity levels resulting from developing in a medium containing menthol. There was a threshold concentration of menthol in the rearing medium below which we found no induced behavioural change.
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  • 3
    ISSN: 1570-7458
    Keywords: sieve element ; salivation ; aphid ; plant resistance ; wheat ; Sitobion fragariae ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Extended sieve element salivation (E1 waveform in the electrical penetration graph) is a characteristic activity during early sieve element punctures, particularly in resistant plants. In order to explore a chemically-mediated mechanism of resistance associated with sieve element salivation, we compared the pattern of feeding behaviour of the aphid, Sitobion fragariae (Walker), on two cultivars of the wheat Triticum aestivum L., with different concentrations of hydroxamic acids (Hx). During 24 h of electronic monitoring, aphids dedicated over 50% of the total time to phloem ingestion from the sieve elements. Total time allocated to E1 in the experiment, time to first E1 within the experiment, time allocated to E1 before a sustained phloem ingestion (E2) and the contribution of sieve element salivation to the phloem phase (E1/[E1+E2]) were significantly higher in the high-Hx cultivar. The increased salivation in plants with higher contents of Hx suggests the existence, at least in this system, of a chemically-mediated sieve element constraint.
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  • 4
    ISSN: 1432-1890
    Keywords: Key words Glomus mosseae ; Hydroponics ; Nitrate uptake ; Root respiration ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Oxygen and CO2 fluxes were measured in hydroponically grown mycorrhizal and non-mycorrhizal Triticum aestivum L. cv. Hano roots. The NO3 – uptake of the plants was used to estimate the amount of root respiration attributable to ion uptake. Plants were grown at 4 mM N and 10 μM P, where a total and viable mycorrhizal root colonisation of 48% and 18%, respectively, by Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe (BEG 107) was observed. The O2 consumption and NO3 – uptake rates were similar and the CO2 release was higher in mycorrhizal than in non-mycorrhizal wheat. This resulted in a significantly higher respiratory quotient (RQ, mol CO2 mol–1 O2) in mycorrhizal (1.27±0.13) than in non-mycorrhizal (0.79±0.05) wheat. As the biomass and N and P concentrations in mycorrhizal and non-mycorrhizal wheat were the same, the higher RQ resulted from the mycorrhizal colonisation and not differences in nutrition per se.
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  • 5
    ISSN: 1432-0789
    Keywords: Key words Phosphate-solubilizing microorganisms ; Mussoorie rock phosphate ; Vesicular-arbuscular mycorrhizae ; Triticum aestivum ; Nutrient-deficient soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The effect of inoculating wheat (Triticum aestivum L.) with the PO4 3–-solubilizing microorganisms (PSM) Bacillus circulans and Cladosporium herbarum and the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus sp. 88 with or without Mussoorie rock phosphate (MRP) amendment in a nutrient-deficient natural sandy soil was studied. In the sandy soil of low fertility root colonization by VAM fungi was low. Inoculation with Glomus sp. 88 improved root colonization. At maturity, grain and straw yields as well as N and P uptake improved significantly following inoculation with PSM or the VAM fungus. These increases were higher on combined inoculation of PSM and the VAM fungus with MRP amendment. In general, a larger population of PSM was maintained in the rhizosphere of wheat in treatments with VAM fungal inoculation and MRP amendment. The results suggest that combined inoculation with PSM and a VAM fungus along with MRP amendment can improve crop yields in nutrient-deficient soils.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 53 (1999), S. 157-175 
    ISSN: 1573-0867
    Keywords: Brassica napus ; Cicer arietinum ; current P ; Lens culinaris ; Lupinus albus ; Lupinus angustifolius ; P concentration response ; P content response ; Pisum sativum ; previous P ; sigmoid response ; single superphosphate ; Triticum aestivum ; Vicia faba ; yield response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus (P) is a major deficiency of soils of south-western Australia (WA). The fertilizer P requirements are not known for grain legumes being evaluated for neutral to alkaline, fine textured soils in WA. To rectify this, glasshouse and field experiments were undertaken to compare the responses of several grain legume species, wheat and canola to applications of single superphosphate and the results are reported in this paper. The glasshouse experiments measured responses of dried tops, harvested at 26 to 42 days after sowing, to P that was freshly-applied (current P) and previously-applied (previous P). Responses in the glasshouse were measured using yield, P concentration and P content (P concentration multiplied by yield) of oven dried tops of the following: wheat (Triticum aestivum), canola (Brassica napus), faba bean (Vicia faba), chickpea (Cicer arietinum), lentil (Lens culinaris), field pea (Pisum sativum), albus lupin (Lupinus albus) and narrow leaf lupin (Lupinus angustifolius). Field experiments in 1994 and 1995 compared seed (grain) yield responses of faba bean, chickpea, lentil, albus lupin and wheat to applications of current P. The P was banded (drilled) with the seed while sowing at 5 cm depth. Canola and wheat produced very large yield responses to increasing applications of current P. Responses were much smaller for albus lupin, faba bean and chickpea. Responses for lentil, narrow leaf lupin and field pea, fell in between responses of the small and large seeded species. Similar trends for responses were obtained as measured using yield, P concentration, or P content. For soils treated with previous P, similar trends were observed as for current P, but differences in yield responses between species were much less marked and the response curves tended to become more sigmoid. In the field experiments, grain yield responses to current P of albus lupin and chickpea were less than that for wheat. Relative to wheat, faba bean was the most responsive grain legume to applications of current P, with lentil producing similar responses to wheat in one experiment at a newly cleared, P deficient site.
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  • 7
    ISSN: 1432-041X
    Keywords: Key words bHLH genes ; Drosophila ; Embryogenesis ; Enhancer of split ; Notch pathway
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  E(spl) bHLH genes are targets of the Notch pathway: they are transcriptionally activated in response to the Notch signal. Yet, during imaginal development, additional regulatory factors appear to modulate transcription resulting in different expression patterns. During early embryogenesis all E(spl) bHLH genes are expressed in roughly the same domain, namely the neurogenic ectoderm. Within this region these seven genes show a highly dynamic, yet distinct transcriptional activity. Our analysis further detected tissue specific expression of some E(spl) genes at later embryonic stages. Prominent differences were observed in the dorsolateral and procephalic neuroectodermal regions as well as in the mesoderm. These observations indicate that other factors in addition to the Notch signal participate in the regulation of the individual E(spl) genes not only in imaginal tissues but also during neuroblast specification and other cell fate determination events in the embryo.
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  • 8
    ISSN: 1432-041X
    Keywords: Key words Delta ; Notch ; Follicle cells ; Oogenesis ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  During Drosophila oogenesis the body axes are determined by signaling between the oocyte and the somatic follicle cells that surround the egg chamber. A key event in the establishment of oocyte anterior-posterior polarity is the differential patterning of the follicle cell epithelium along the anterior-posterior axis. Both the Notch and epithelial growth factor (EGF) receptor pathways are required for this patterning. To understand how these pathways act in the process we have analyzed markers for anterior and posterior follicle cells accompanying constitutive activation of the EGF receptor, loss of Notch function, and ectopic expression of Delta. We find that a constitutively active EGF receptor can induce posterior fate in anterior but not in lateral follicle cells, showing that the EGF receptor pathway can act only on predetermined terminal cells. Furthermore, Notch function is required at both termini for appropriate expression of anterior and posterior markers, while loss of both the EGF receptor and Notch pathways mimic the Notch loss-of-function phenotype. Ectopic expression of the Notch ligand, Delta, disturbs EGF receptor dependent posterior follicle cell differentiation and anterior-posterior polarity of the oocyte. Our data are consistent with a model in which the Notch pathway is required for early follicle cell differentiation at both termini, but is then repressed at the posterior for proper determination of the posterior follicle cells by the EGF receptor pathway.
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  • 9
    ISSN: 1432-041X
    Keywords: Key words Synapse ; Drosophila ; Immunoglobulin superfamily ; Axonal transport ; Neurosecretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Hikaru genki (HIG) is a putative secreted protein of Drosophila that belongs to immunoglobulin and complement-binding protein superfamilies. Previous studies reported that, during pupal and adult stages, HIG protein is synthesized in subsets of neurons and appears to be secreted to the synaptic clefts of neuron-neuron synapses in the central nervous system (CNS). Here we report the analyses of distribution patterns of HIG protein at embryonic and larval stages. In embryos, HIG was mainly observed in subsets of neurons of the CNS that include pCC interneurons and RP5 motorneurons. At third instar larval stage, this protein was detected in a limited number of cells in the brain and ventral nerve cord. Among them are the motorneurons that extend their axons to make neuromuscular junctions on body wall muscle 8. Immunoelectron microscopy showed that these axonal processes as well as the neuromuscular terminals contain numerous vesicles with HIG staining, suggesting that HIG is in a pathway of secretion at this stage. Some neurosecretory cells were also found to express this protein. These data suggest that HIG functions in the nervous system through most developmental stages and may serve as a secreted signalling molecule to modulate the property of synapses or the physiology of the postsynaptic cells.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 209 (1999), S. 218-225 
    ISSN: 1432-041X
    Keywords: Key words α-catenin ; Drosophila ; Green fluorescent protein (GFP) ; Adherens junction ; Epithelial morphogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Cell-cell adherens junctions (AJs), comprised of the cadherin-catenin adhesion system, contribute to cell shape changes and cell movements in epithelial morphogenesis. However, little is known about the dynamic features of AJs in cells of the developing embryo. In this study, we constructed Dα-catenin fused with a green fluorescent protein (Dα-catenin-GFP), and found that it targeted apically located AJ-based contacts but not other lateral contacts in epithelial cells of living Drosophila embryos. Using time-lapse fluorescence microscopy, we examined the dynamic performance of AJs containing Dα-catenin-GFP in epithelial morphogenetic movements. In the ventral ectoderm of stage 11 embryos, concentration and deconcentration of Dα-catenin-GFP occurred concomitantly with changes in length of AJ contacts. In the lateral ectoderm of embryos at the same stage, dynamic behaviour of AJs was concerted with division and delamination of sensory organ precursor (SOP) cells. Moreover, changes in patterns of AJ networks during tracheal extension could be followed. Finally, we utilized Dα-catenin-GFP to precisely observe the defects in tracheal fusion in shotgun mutants. Thus, the Dα-catenin-GFP fusion protein is a helpful tool to simultaneously observe morphogenetic movements and AJ dynamics at high spatio-temporal resolution.
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  • 11
    ISSN: 1432-041X
    Keywords: Key words Deformed ; Drosophila ; Embryogenesis ; Tribolium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We have analyzed the Tribolium castaneum ortholog of the Drosophila homeotic gene Deformed (Dfd) and determined its expression pattern during embryogenesis in this beetle. Tc Deformed (Tc Dfd) is expressed in the blastoderm and the condensing germ rudiment in a region that gives rise to gnathal segments. During germ band extension Tc Dfd is expressed in the mandibular and maxillary segments, their appendages, and the dorsal ridge. Comparison of insect Dfd protein sequences reveals several highly conserved regions. To determine whether common molecular features reflect conserved regulatory functions we used the Gal4 system to express the Tribolium protein in Drosophila embryos. When Tc Dfd is expressed throughout embryonic ectoderm under the control of P69B, the beetle protein autoregulates the endogenous Dfd gene. In addition, the Drosophila proboscipedia gene (a normal target of Dfd) is ectopically activated in the antennal and thoracic segments. We also compared the ability of the beetle and fly proteins to rescue defects in Dfd – mutants by expressing each throughout the embryonic during embryogenesis. Both proteins rescued Dfd – defects to the same extent in that they each restore the development of mouth hooks and cirri, as well as cause gain-of-function abnormalities of posterior mouth parts. As before, pb was ectopically activated in the antennal segment. This is the first demonstration of the ability of a heterologous homeotic selector protein to directly regulate a target gene independent of an endogenous Drosophila autoregulatory loop.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Molecular biology reports 26 (1999), S. 103-111 
    ISSN: 1573-4978
    Keywords: arthropod ; crustacean ; Drosophila ; insect ; lobster ; multicatalyic proteinase ; proteasome ; ubiquitin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recent work on structural/functional relationships in arthropod proteasomes is reviewed. Taking advantage of our ability to induce a stable, proteolytically-active conformation of the lobster proteasome, the structures of basal and heat-activated complexes were probed with exogenous proteases. Increased sensitivity to chymotrypsin and trypsin showed that heat activation induced a more ‘open’ conformation, allowing entry of large substrates into the catalytic chamber. In Drosophila, the effects of two developmental mutant alleles (DTS-7 and DTS-5) encoding proteasome subunits (Z and C5, respectively) on the subunit composition and catalytic activities of the enzyme were examined. Both qualitative and quantitative differences in compositions between wild-type (+/+) and heterozygotes (+/DTS) indicated that incorporation of mutant subunits alters post-translational modifications of the complex. Catalytic activities, however, were similar, which suggests that the developmental defect involves other proteasome properties, such as intracellular localization and/or interactions with endogenous regulators. A hypothetical model in which DTS subunits act as poison subunits is presented.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Molecular biology reports 26 (1999), S. 147-157 
    ISSN: 1573-4978
    Keywords: Drosophila ; jun ; fos ; AP-1 ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mammalian proto-oncogenes c-jun and c-fos are situated at the end of multiple signal transduction pathways and activation of their products Jun and Fos, components of the transcription factor AP-1, are able to regulate gene transcription in response to extracellular stimuli. Djun and Dfos, the products of the Drosophila proto-oncongenes Djun and Dfos, are similar in size and sequence to their mammalian counterparts c-Jun and c-Fos and are related to their mammalian counterparts by their antigenic properties. However, very little is known about how they are regulated through signal transduction pathways. This paper has investigated the response of their mRNA abundance levels to three signal transduction pathways in Drosophila cultured cells. Various agonists and anagonists that stimulate and inhibit specific enzymes in the pathways have been tested. The results suggest that Djun and Dfos mRNA are continuously expressed and their abundance levels are transiently regulated by multiple signaling pathways, the peak response coming at 1–2 hours after perturbation. Dfos is more highly regulated than Djun which is only modulated. The receptor tyrosine kinase pathways positively regulate Dfos and Djun. The cAMP-mediated pathway positively regulates Dfos but negatively regulates Djun. The protein kinase C-activated pathway does not affect Djun whereas it negatively regulates Dfos.
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  • 14
    ISSN: 1432-1890
    Keywords: Key words Arbuscular mycorrhiza ; Hordeum vulgare ; Triticum aestivum ; Glomus intraradices ; Mycorrhiza-helper bacteria ; Secondary compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Colonization of Hordeum vulgare L. cv. Salome (barley)and Triticum aestivum L. cv. Caprimus (wheat) roots by the arbuscular mycorrhizal fungus Glomus intraradices Schenck & Smith leads to de novo synthesis of isoprenoid cyclohexenone derivatives with blumenin [9-O-(2′-O-β-glucuronosyl)-β-glucopyranoside of 6-(3-hydroxybutyl)-1,1,5-trimethyl-4-cyclohexen-3-one] as the major constituent and to transient accumulation of hydroxycinnamate amides (4-coumaroylagmatine and -putrescine). Accumulation of these compounds in mycorrhizal wheat roots started 2 weeks after sowing together with the onset of arbuscule formation and proceeded with mycorrhizal progression. Highest levels were reached in 3- to 4-week-old secondary roots (root branches of first and higher order) characterized by the formation of vesicles. In the final developmental stages, the fungus produced massive amounts of spores, enclosing the stele of older root parts (older than 5 weeks) characterized by cortical death. In these root parts, the secondary compounds were detected in trace amounts only, indicating that they were located in the cortical tissues. Some rhizosphere bacteria tested, i.e. Agrobacterium rhizogenes, Pseudomonas fluorescens, and Rhizobium leguminosarum, markedly stimulated both fungal root colonization and blumenin accumulation, thus, acting as mycorrhiza-helper bacteria (MHB). Application of blumenin itself strongly inhibited fungal colonization and arbuscule formation at early stages of mycorrhiza development. This was associated with a markedly reduced accumulation of the hydroxycinnamate amides 4-coumaroylputrescine and -agmatine. The results suggest that both the isoprenoid and the phenylpropanoid metabolism are closely linked to the developmental stage and the extent of fungal colonization. Their possible involvement in the regulation of mycorrhiza development is discussed.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 98 (1999), S. 472-477 
    ISSN: 1432-2242
    Keywords: Key words QTL ; Ear emergence time ; Plant height ; Recombinant substitution line ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Chromosome 5A of wheat carries major gene loci for agronomic traits including the vernalization requirement (Vrn-A1) and ear morphology (Q). To determine whether the genetic variation for ear emergence time and plant height is attributable to either of these major genes as pleiotropic effects or independent QTL, we combined a RFLP map constructed from 120 recombinant substitution lines derived from a cross between ‘Chinese Spring’ (Cappelle-Desprez 5A) and CS(Triticum spelta 5A) with data collected from field trials over 3 years. For ear emergence time the main effects on flowering time were by Vrn-A1 and QEet.ocs-5A.1, the latter a QTL in the 28.6-cM Xcdo584/Q interval linked to Q by less than 10 cM. The CS(T. spelta 5A) allele at QEet.ocs-5A.1 contributed to an earlier ear emergence time by 2.7–6.0 days, which was approximately equal to the effects of Vrn-A1. For plant height, three QTLs were identified on the long arm and linked in repulsion. The CS(T. spelta 5A) allele at Vrn-A1 or closely linked to Xfba068 contributed to a height reduction of 3.5–6.1 cm, whereas both the Q allele and Qt.ocs-5A.1 allele within the Xcdo1088/Xbcd9 interval from CS(Cappelle-Desprez 5A) produced a shorter plant. When plant height was partitioned into culm length and ear length, the Vrn-A1 allele and CS(Cappelle-Desprez 5A) allele at QCl.ocs-5A.1 within the Xcd1088/Xbcd9 interval were found to contribute to a shorter culm. CS(T. spelta 5A) allele at q was a major determinant of a long ear, together with minor effects at QEl.ocs-5A.1 within the Xcdo1088/Xbcd9 interval.
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  • 16
    ISSN: 1432-2242
    Keywords: Key words Erysiphe graminis ; Powdery mildew resistance ; QTL ; Triticum aestivum ; Triticum spelta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Powdery mildew is one of the major diseases of wheat in regions with a maritime or semi-continental climate and can strongly affect grain yield. The attempt to control powdery mildew with major resistance genes (Pm genes) has not provided a durable resistance. Breeding for quantitative resistance to powdery mildew is more promising, but is difficult to select on a phenotypic basis. In this study, we mapped and characterised quantitative trait loci (QTLs) for adult-plant powdery mildew resistance in a segregating population of 226 recombinant inbred lines derived from the cross of the Swiss wheat variety Forno with the Swiss spelt variety Oberkulmer. Forno possibly contains the Pm5 gene and showed good adult-plant resistance in the field. Oberkulmer does not have any known Pm gene and showed a moderate susceptible reaction. Powdery mildew resistance was assessed in field trials at two locations in 1995 and at three locations in 1996. The high heritability (h2=0.97) for powdery mildew resistance suggests that the environmental influence did not affect the resistance phenotype to a great extent. QTL analysis was based on a genetic map containing 182 loci with 23 linkage groups (2469 cM). With the method of composite interval mapping 18 QTLs for powdery mildew resistance were detected, explaining 77% of the phenotypic variance in a simultaneous fit. Two QTLs with major effects were consistent over all five environments. One of them corresponds to the Pm5 locus derived from Forno on chromosome 7B. The other QTL on 5A, was derived from the spelt variety Oberkulmer and did not correspond to any known Pm gene. In addition, five QTLs were consistent over three environments, and six QTLs over two environments. The QTL at the Pm5 locus showed a large effect, although virulent races for Pm5 were present in the mixture of isolates. Molecular markers linked with QTLs for adult-plant resistance offer the possibility of simultaneous marker-assisted selection for major and minor genes.
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  • 17
    ISSN: 1432-2242
    Keywords: Key words Aegilops tauschii ; Triticum aestivum ; Genetic mapping ; Molecular markers ; Agronomically important genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Aegilops tauschii is the diploid D-genome progenitor of bread wheat (Triticum aestivum L. em Thell, 2n=6x=42, AABBDD). A genetic linkage map of the Ae. tauschii genome was constructed, composed of 546 loci. One hundred and thirty two loci (24%) gave distorted segregation ratios. Sixty nine probes (13%) detected multiple copies in the genome. One hundred and twenty three of the 157 markers shared between the Ae. tauschii genetic and T. aestivum physical maps were colinear. The discrepancy in the order of five markers on the Ae. tauschii 3DS genetic map versus the T. aestivum 3D physical map indicated a possible inversion. Further work is needed to verify the discrepancies in the order of markers on the 4D, 5D and 7D Ae. tauschii genetic maps versus the physical and genetic maps of T. aestivum. Using common markers, 164 agronomically important genes were assigned to specific regions on Ae. tauschii linkage, and T. aestivum physical, maps. This information may be useful for map-based cloning and marker-assisted plant breeding.
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  • 18
    ISSN: 1432-2242
    Keywords: Key words Lodging ; Morphological traits ; QTL ; Triticum aestivum ; Triticum spelta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Lodging can strongly affect both the grain yield and the quality of wheat. Lodging represents a quantitative trait and is difficult to assess on a phenotypic basis. Marker-assisted selection (MAS) could therefore become an important tool in breeding for lodging resistance. In this study, we mapped and characterised quantitative trait loci (QTLs) for lodging resistance, as well as morphological traits correlated with lodging, in a segregating population of 226 recombinant inbred lines derived from the cross of the lodging-resistant wheat variety Forno with the susceptible spelt variety Oberkulmer. Lodging, plant height, leaf width, leaf-growth habit, culm stiffness, culm swinging, culm thickness, days to ear emergence and days to flowering were assessed in field trials at two locations in 1996 and at one location in 1997. Additionally, at one location weight and length parameters were also assessed. Plant height and culm stiffness explained 77% of the phenotypic variance of lodging in a multiple regression model over all three environments. QTL analysis of lodging and morphological parameters was based on a genetic map containing 230 loci with 23 linkage groups (2469 cM). With the method of composite interval mapping nine QTLs for lodging resistance were detected, explaining 63% of the phenotypic variance in a simultaneous fit. Seven of these QTLs coincided with QTLs for morphological traits, reflecting the correlations between these traits and lodging. In our population the most efficient way to improve lodging resistance would be by a combination of indirect selection on plant height and culm stiffness together with MAS on the two QTLs for lodging resistance which did not coincide with QTLs for morphological traits.
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  • 19
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    Theoretical and applied genetics 98 (1999), S. 1248-1252 
    ISSN: 1432-2242
    Keywords: Key words Wheat ; Chromosome sorting ; Chromosome isolation ; Aneuploids ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We are reporting the successful isolation of wheat chromosome arm 1DS by flow cytometry. A chromosome suspension was prepared for the 1DS ditelosomic line and the normal ‘Chinese Spring’ (CS) by chopping 2-day-old root tip meristems, synchronized by hydroxyurea, in HEPES-magnesium sulfate buffer containing propidium iodide. Chromosomes were analyzed and sorted with a FACS Vantage flow cytometer and cell sorter. An extra peak was observed in the flow karyotype of the ditelosomic line that was absent in ‘CS’. The estimated size of chromosomes from the extra peak matched with the expected size of chromosome 1DS. Chromosomes from the putative 1DS peak were analyzed by both fluorescent microscopy and N-banding analysis. A total of 571 chromosomes from two separate experiments were analyzed, and all were observed to be telosomics except for 2 which were broken. About 82% of these telosomics showed the diagnostic N-band of 1DS, the remaining were unbanded and are probably also 1DS. This strategy can also be used to sort other wheat arms.
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  • 20
    ISSN: 1432-2242
    Keywords: Key words Transgenic wheat ; Triticum aestivum ; Tritordeum ; Transgene inheritance ; Marker gene stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The stability and heritability of three marker genes was investigated in a population of twelve independent transgenic cereal lines (six wheat and six tritordeum). Integration patterns, inheritance of structural transgenes and inheritance of expression were analysed in the T0 and T1 generations for all 12 lines. Transmission and expression were analysed in the T2 generation for 9 lines and in the T3 generation for the six wheat lines. Inheritance of integration patterns was highly stable, and transmission of the transgenes and inheritance of their expression followed Mendelian ratios in the majority of lines. A gradual reduction in uidA expression was observed over three generations, which was not accompanied by a similar reduction in bar expression. Some unexpected phenomena associated with transgene inheritance were also observed and are discussed.
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  • 21
    ISSN: 1573-9368
    Keywords: low molecular weight glutenin promoter ; particle bombardment ; transgene expression ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transgenic wheat plants from specific cultivars can now be routinely engineered in many laboratories. However, our understanding of the factors controlling transgene expression and stability in wheat compared to other cereals is rather limited. Only a few promoters have been tested in transgenic wheat, and relatively little is known of their relative activities and expression parameters. In the present study, the spatial and temporal properties of one heterologous constitutive promoter and one seed‐specific wheat promoter were investigated. We generated constructs with the reporter gene gusA (β‐glucuronidase) driven by: (a) the constitutive maize ubiquitin‐1 (ubi‐1) promoter, and (b) two different‐sized fragments of the seed‐specific low molecular weight glutenin (LMWG1D1) promoter from wheat. The activities of all three promoter constructs were comparable in endosperm tissue. A detailed analysis of spatial and temporal properties of the promoters is described. Heat shock treatment of transgenic plants carrying the ubi‐1: gusA construct resulted in a significant elevation in the levels of GUS activity. The inheritance of transgene expression levels and stability was evaluated over four generations, as a function of transgene integration patterns and copy number.
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  • 22
    ISSN: 1617-4623
    Keywords: Key words Molybdenum cofactor biosynthesis ; Drosophila ; cinnamon ; cnx1 ; GEPHYRIN
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Molybdoenzymes are involved in a variety of essential pathways including nitrate assimilation, sulfur and/or purine metabolism and abscisic acid biosynthesis. Most organisms produce several such enzymes requiring a molybdopterin cofactor for catalytic function. Mutations that result in a lack of the molybdopterin cofactor display a pleiotropic loss of molybdoenzyme activities, and this phenotype has been used to identify genes involved in cofactor biosynthesis or utilization. Although several cofactor genes have been analyzed in prokaryotes, much less is known concerning eukaryotic molybdenum cofactor (MoCF) genes. This work is focused on the Drosophila MoCF gene cinnamon (cin) which encodes a multidomain protein, CIN, that shows significant similarity to three proteins encoded by separate prokaryotic MoCF genes. These domains are also present in the product of cnx1, an Arabidopsis MoCF gene, and in GEPHYRIN, a rat protein thought to organize the glycine receptor, GlyR, within the postsynaptic membrane. Since this apparent consolidation of separate prokaryotic genes into a single eukaryotic gene is a feature of other conserved metabolic pathways, we wished to determine whether the protein's function is also conserved. This report shows that the plant gene cnx1 can rescue both enzymatic and physiological defects of Drosophila carrying cin mutations, indicating that the two genes serve similar or identical functions. In addition, we have investigated the relationship between CINNAMON and GEPHYRIN, using immunohistochemical methods to localize the CIN protein in Drosophila embryos. Most of the CIN protein, like GEPHYRIN in the rat CNS, is localized to the cell borders and shows a tissue-specific pattern of expression. In a parallel study, antibody to GEPHYRIN revealed the same tissue-specific expression pattern in fly embryos. Both antibodies show altered staining patterns in cin mutants. Taken together, these results suggest that GEPHYRIN may also carry out a MoCF-related function.
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  • 23
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    Molecular genetics and genomics 262 (1999), S. 618-622 
    ISSN: 1617-4623
    Keywords: Key words Telomeric retrotransposons ; HeT-A elements ; Centric heterochromatin ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated two yeast artificial chromosome (YAC) clones from Drosophila melanogaster that contain a small amount of dodeca satellite (a satellite DNA located in the centromeric region of chromosome 3) and sequences homologous to the telomeric retrotransposon HeT-A. Using these YACs as probes for fluorescence in situ hybridization to mitotic chromosomes, we have localized these HeT-A elements to the centric heterochromatin of chromosome 3, at region h55. The possible origin of these telomeric elements in a centromeric position is discussed.
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  • 24
    ISSN: 1618-2545
    Keywords: BLB light ; conidiogenesis ; Fusarium globosum ; subtropical Japan ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The second report ofFusarium globosum is based on strains isolated from wheat in Ishigaki Island, Okinawa, in subtropical Japan. Morphological features of the Japanese isolates are described. These strains show different reactions in conidiogenesis to light conditions. Under continuous BLB light, falcate sporodochial conidia are typically induced, but production of aerial globose conidia is suppressed. In two of the strains, clavate conidia became longer under BLB light. Application of both, complete darkness and continuous BLB light, is recommended as standard light conditions to cultureFusarium isolates.
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  • 25
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    Apoptosis 4 (1999), S. 239-243 
    ISSN: 1573-675X
    Keywords: Apoptosis ; cell survival ; differentiation ; Drosophila ; EGFR ; hid ; ras.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The Drosophila epidermal growth factor receptor (EGFR), functioning through the Ras/Raf/MAPK pathway, promotes cell proliferation and differentiation. Recent work has demonstrated that EGFR functions via the same Ras/Raf/MAPK pathway to promote cell survival. This review summarizes the role of EGFR in differentiation and survival during Drosophila eye development.
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  • 26
    ISSN: 1573-6857
    Keywords: P element ; repressor ; maternal effect ; Drosophila ; population
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract As part of our effort to monitor changes in the clinal pattern of P element-associated traits in eastern Australian Drosophila melanogaster, we investigated the genomic P elements of 293 isofemale lines collected in the period 1991–1994 from 45 localities. P elements were present in many copies in all genomes examined, with full-size P and KP element size classes accounting for the large majority. SR elements were not present in at least 92% of the lines tested. South of about 26° south Latitude (°SLat), the ratio of KP to full-size P elements (KP/P ratio) increased, correlating weakly with the P-M phenotypes of the populations, from moderately P populations (26–29°SLat) to M populations (37–38°SLat) North of 26°SLat, in weak P populations, the KP/P ratio was higher than between 26 and 29°Slat. The KP/P ratio appears to be higher in the northern populations than it was when previous studies were done. Overall, a high KP/P ratio among lines correlated roughly with a lack of P activity, but it also correlated with reduced repressor function. In a sample of 30 lines, a maternal effect of repressor function did not show a pattern with latitude, nor with KP/P ratio, nor with presence or absence of P activity.
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    Genetica 105 (1999), S. 43-62 
    ISSN: 1573-6857
    Keywords: distribution ; Drosophila ; retrotransposon ; transposable element
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We present a global analysis of the distribution of 43 transposable elements (TEs) in 228 species of the Drosophila genus from our data and data from the literature. Data on chromosome localization come from in situ hybridization and presence/absence of the elements from southern analyses. This analysis shows great differences between TE distributions, even among closely related species. Some TEs are distributed according to the phylogeny of their host specie; others do not entirely follow the phylogeny, suggesting horizontal transfers. A higher number of insertion sites for most TEs in the genome of D. melanogaster is observed when compared with that in D. simulans. This suggests either intrinsic differences in genomic characteristics between the two species, or the influence of differing effective population sizes, although biases due to the use of TE probes coming mostly from D. melanogaster and to the way TEs are initially detected in species cannot be ruled out. Data on TEs more specific to the species under consideration are necessary for a better understanding of their distribution in organisms and populations.
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  • 28
    ISSN: 1573-6857
    Keywords: Drosophila ; hobo ; hot spot ; integration specificity ; transposable elements
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract We analyzed the integration specificity of the hobo transposable element of Drosophila melanogaster. Our results indicate that hobo is similar to other transposable elements in that it can integrate into a large number of sites, but that some sites are preferred over others, with a few sites acting as integration hot spots. A comparison of DNA sequences from 112 hobo integration sites identified a consensus sequence of NTNNNNAC, but this consensus was insufficient to account for the observed integration specificity. To begin to define the parameters affecting hobo integration preferences, we analyzed sequences flanking a donor hobo element, as well as sequences flanking a hobo integration hot spot for their relative influence on hobo integration specificity. We demonstrate experimentally that sequences flanking a hobo donor element do not influence subsequent integration site preference, whereas, sequences contained within 31 base pairs flanking an integration hot spot have a significant effect on the frequency of integration into that site. However, sequence analysis of the DNA flanking several hot spots failed to identify any common sequence motif shared by these sites. This lack of primary sequence information suggests that higher order DNA structural characteristics of the DNA and/or chromatin may influence integration site selection by the hobo element.
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    Genetica 105 (1999), S. 239-248 
    ISSN: 1573-6857
    Keywords: transposable elements ; LTR-retroelements ; rearrangements ; population genetics ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 297 element Southern pattern modifications previously detected in mutation accumulation lines of Drosophila melanogaster were further investigated by in situ hybridisation, Southern blotting with different combinations of genomic digest-probe, and PCR. Only one out of the nine pattern modifications studied could be interpreted as an excision and was detectable by in situ hybridisation to polytene chromosomes. Results were consistent with most pattern modifications being small rearrangements within the body of the element. In agreement with the existence of spontaneous rearrangements of this kind is the observation that many genomic copies of element 297 are defective and these are not limited to heterochromatin. These findings have important implications for the models of transposable element (TE) number regulation as well as for the study of genome evolution.
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  • 30
    ISSN: 1573-6857
    Keywords: colonization ; Drosophila ; dynamic ; natural populations ; transposable elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Drosophila simulans presents a large variation in copy number among various transposable elements (TEs) and among natural populations for a given element. Some elements such as HMS beagle, blood, flea, tirant, coral, prygun jockey, F, nomade and mariner are absent in most populations, except in one or two which have copies on their chromosome arms. This suggests that some TEs are being awakened in D. simulans and are in the process of invading the species while it is colonizing the world. The elements 412 and roo/B104 present a wide insertion polymorphism among D. simulans populations, but only the 412 copy number follows a temperature cline. One population (Canberra from Australia) has a very high copy number for the 412 element and for many other TEs as well, indicating that some populations may have lost control of some of their TEs. While the 412 transposition rate is similar in all populations, its transcription level throughout developmental stages varies with populations, depending on copy number. Populations with 412 copy number higher than 10–12 exhibit co-suppression, while the expression in populations with lower numbers depends on the insertion location. All these results suggest genomic invasions by 412 and other TEs during the worldwide spread of the D. simulans species.
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  • 31
    ISSN: 1573-6857
    Keywords: Drosophila ; genome evolution ; molecular domestication ; P element ; transposable elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transposable elements are short but complex pieces of DNA or RNA containing a streamlined minimal-genome with the capacity for its selfish replication in a foreign genomic environment. Cis-regulatory sections within the elements orchestrate tempo and mode of TE expression. Proteins encoded by TEs mainly direct their own propagation within the genome by recruitment of host-encoded factors. On the other hand, TE-encoded proteins harbor a very attractive repertoire of functional abilities for a cell. These proteins mediate excision, replication and integration of defined DNA fragments. Furthermore, some of these proteins are able to manipulate important host factors by altering their original function. Thus, if the host genome succeeds in domesticating such TE-encoded proteins by taming their ‘anarchistic behavior,’ such an event can be considered as an important evolutionary innovation for its own benefit. In fact, the domestication of TE-derived cis-regulatory modules and protein coding sections took place repeatedly in the course of genome evolution. We will present prominent cases that impressively demonstrate the beneficial impact of TEs on host biology over evolutionary time. Furthermore, we will propose that molecular domestication might be considered as a resumption of the same evolutionary process that drove the transition from ‘primitive genomes’ to ‘modern’ ones at the early dawn of life, that is, the adaptive integration of a short piece of autonomous DNA into a complex regulatory network.
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  • 32
    ISSN: 1617-4623
    Keywords: Key words Mitochondrial proteins ; Nuclear genes ; Drosophila ; Evolutionary conservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract As a first step towards using cross-species comparison to complete the inventory of the nuclear genes that encode mitochondrial polypeptides, and ultimately to understand their function through systematic molecular and genetic analysis in a model organism of choice, we report here the characterization of 41 Drosophila melanogaster cDNAs. These cDNAs were isolated by screening an ovarian expression library with antibodies against mitochondrial proteins and identify 17 novel Drosophila genes. The deduced amino acid sequences encoded by the majority of these cDNAs turned out to show significant homology to mitochondrial proteins previously identified in other species. Among others, ORFs putatively encoding six different subunits of ATP synthase and three NADH:ubiquinone reductase subunits were detected. By in situ hybridization, all cDNAs were mapped to single bands on polytene chromosomes, thus identifying candidate Drosophila genes required for mitochondrial biogenesis and maintenance. A search of the Human Gene Index database made it possible in most cases to align the entire Drosophila coding sequence with a human consensus sequence, suggesting that the cDNAs originate from insect counterparts of expressed mammalian genes. Our experimental strategy represents an efficient approach to the identification and interspecies comparison of genes encoding products targeted to the mitochondrion.
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  • 33
    ISSN: 1573-5036
    Keywords: genotypic variation ; Secale cereale ; Triticum aestivum ; Triticum durum ; zinc efficiency ; zinc deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effect of zinc (Zn) nutritional status on uptake of inorganic 65Zn was studied in rye (Secale cereale, cv. Aslim), three bread wheat (Triticum aestivum, cvs. Dagdas, Bezostaja, BDME-10) and durum wheat (Triticum durum, cv. Kunduru-1149) cultivars grown for 13 days in nutrient solution under controlled environmental conditions. The cultivars were selected based on their response to Zn deficiency and to Zn fertilization in calcareous soils under field conditions. When grown in Zn-deficient calcareous soil in the field, the rye cultivar had the highest, and the durum wheat the lowest Zn efficiency. Among the bread wheats, BDME-10 showed higher susceptibility to Zn deficiency and Bezostaja and Dagdas were less affected by Zn deficiency. Similarly to field conditions, in nutrient solution visual Zn deficiency symptoms (i.e. necrotic lesions on leaf blade) appeared to be more severe in Kunduru-1149 and BDME-10 and less severe in rye cultivar Aslim. Under Zn deficiency, shoot concentrations of Zn were similar between all cultivars. Cultivars with adequate Zn supply did not differ in uptake and root-to-shoot translocation rate of 65Zn, but under Zn deficiency there were distinct differences; rye showed the highest rate of Zn uptake and the durum wheat the lowest. In the case of bread wheat cultivars, 65Zn uptake rate was about the same and not related to their differential Zn efficiency. Under Zn deficiency, rye had the highest rate of root-to-shoot translocation of 65Zn, while all bread and durum wheat cultivars were similar in their capacity to translocate 65Zn from roots to shoots. When Zn2+ activity in uptake solution ranged between 117 p M and 34550 pM, Zn-efficient and Zn-inefficient bread wheat genotypes were again similar in uptake and root-to-shoot translocation rate of 65Zn. The results indicate that high Zn efficiency of rye can be attributed to its greater Zn uptake capacity from soils. The inability of the durum wheat cultivar Kunduru-1149 to have a high Zn uptake capacity seems to be an important reason for its Zn inefficiency. Differential Zn efficiency between the bread wheat cultivars used in this study is not related to their capacity to take up inorganic Zn.
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    Plant and soil 215 (1999), S. 65-72 
    ISSN: 1573-5036
    Keywords: barley ; boron deficiency ; Hordeum vulgare ; Triticum aestivum ; variation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Responses of a range of barley (Hordeum vulgare L.) genotypes to boron (B) deficiency were studied in two experiments carried out in sand culture and in the field at Chiang Mai, Thailand. In experiment 1, two barley genotypes, Stirling (two-row) and BRB 2 (six-row) and one wheat (Triticum aestivum L.) genotype, SW 41, were evaluated in sand culture with three levels of applied B (0, 0.1 and 1.0 μM B) to the nutrient solution. It was found that B deficiency depressed flag leaf B concentration at booting, grain number and grain yield of all genotypes. In barley Stirling, B deficiency also depressed number of spikes plant-1, spikelets spike-1 and straw yield. However, no significant difference between genotypes in flag leaf B concentration was found under low B treatments. Flag leaf B concentration below 4 mg kg-1 was associated with grain set reduction and could, therefore, be used as a general indicator for B status in barley. In experiment 2, nine barley and two wheat genotypes were evaluated in the field on a low B soil with three levels of B. Boron levels were varied by applying either 2 t of lime ha-1 (BL), no B (B0) or 10 kg Borax ha-1 (B+) to the soil prior to sowing. Genotypes differed in their B response for grain spike-1, grain spikelet-1 and grain set index (GSI). The GSI of the B efficient wheat, Fang 60, exceeded 90% in all B treatments. The B inefficient wheat SW 41 and most of the barley genotypes set grain normally (GSI 〉80%) only at the B+. In B0 GSI of the barley genotypes ranged from 23% to 84%, and in BL from 19% to 65%. Three of the barley with severely depressed GSI in B0 and BL also had a decreased number of spikelets spike-1. In experiment 3, 21 advanced barley lines from the Barley Thailand Yield Nursery 1997/98 (BTYN 1997/98) were screened for B response in sand culture with no added B. Grain Set Index of the Fang 60 and SW 41 checks were 98 and 65%, respectively, and GSI of barley lines ranged between 5 and 90%. One advanced line was identified as B efficient and two as moderately B efficient. The remaining lines ranked between moderately inefficient to inefficient. These experiments have established that there is a range of responses to B in barley genotypes. This variation in the B response was observed in vegetative as well as reproductive growth. Boron efficiency should be considered in breeding and selection of barley in low B soils.
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    Euphytica 108 (1999), S. 91-95 
    ISSN: 1573-5060
    Keywords: amylose content ; granule-bound starch synthase ; null alleles ; Triticum aestivum ; Wx loci
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The Wx locus controls amylose synthesis in the cereal endosperm. Hexaploid wheat (Triticum aestivum L.) has the three Wx loci on chromosomes 7A ( Wx-A1), 4A (Wx-B1) and 7D (Wx-D1). To verify the effects of null alleles on reducing amylose content and determine the amylose synthesis capacity of each Wx gene independently and accurately, we produced eight possible types of recombinant lines carrying different null alleles at the Wx loci under the ‘Chinese Spring’ genetic background. Amylose content varied from 0% of the waxy ‘Chinese Spring’ to 25% of the ‘Chinese Spring’ normal type. The reducing effect of the single null alleles was the largest in Wx-B1b, and there was no significant difference between Wx-A1b and Wx-D1b. More than 3% reductions in amylose content were detected in the double null types. The results of the double null lines further demonstrated that for the capacity of amylose synthesis, Wx-B1a predominates and produces 21–22% amylose, followed by Wx-D1a (20–21%) and Wx-A1a (15–18%). These significant differences were partly correlated with variation in the amounts of the Wx proteins produced by different Wx genes. However, comparisons of the double null lines with the single null or normal lines indicated that amylose content was not linearly proportional to the number of the Wx genes, suggesting that the Wx genes act in an epistatic manner.
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    Plant growth regulation 28 (1999), S. 129-132 
    ISSN: 1573-5087
    Keywords: dormancy ; Lactuca sativa ; lettuce seeds ; Brassica napus ; rapeseed ; combustion products ; Salix viminalis ; Themeda triandra ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In darkness, dormancy was imposed on seeds of lettuce (Lactuca sativa L. cv. Grand rapids) by high temperature and on seeds of oilseed rape (Brassica napus L. cv. Apex) by osmotic stress using polyethylene glycol (PEG 8000). In both cases, dormancy was broken by incubating the seeds in aqueous extracts of combustion products from Salix viminalis wood chips or Themeda triandra leaves. Dormancy of rapeseed, but not lettuce, was also broken by a solution of smoke from burnt straw of Triticum aestivum. The greatest stimulation from burnt vegetation was achieved with an aqueous extract of pyrolysed willow wood chips, which had been subjected to temperatures of up to 800 °C during combustion in a down-draught gasifier. This suggests that some biologically active substances obtained from combustion of plant tissues are highly heat-stable.
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  • 37
    ISSN: 1573-5087
    Keywords: cortical fibre cell ; gibberellic acid ; spring wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The role of gibberellic acid (GA) in differentiation and secondary cell-wall deposition of fibre cells of spring wheat (Triticum aestivum) culms was studied using applications of GA and chlormequat (a GA biosynthesis inhibitor). In certain genotypes, higher GA levels may increase the number of cortical fibre cell files by changing cell fate from parenchyma to fibre, and induce thicker secondary cell-walls.
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    Genetic resources and crop evolution 46 (1999), S. 469-475 
    ISSN: 1573-5109
    Keywords: foliar blight ; germplasm ; resistance ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract One thousand three hundred and eighty-seven spring wheat germplasm (Triticum aestivum L.) lines belonging to the Indian and CIMMYT wheat programmes were evaluated for their tolerance to foliar blight disease for three consecutive years i.e., from 1994 to 1997. Disease severity at six different growth stages, beginning from tillering to late milk stage, was recorded. None of the genotypes showed immunity to the disease. Of 43 lines showing resistant reaction, a major proportion (25) was represented by CIMMYT material. Comparatively, Indian germplasm lines tended to be more susceptible at more advanced growth stages. Area Under Disease Progress Curve (AUDPC) and Apparent Infection Rate (r) values of resistant lines were much lower than those of susceptible ones, but lower AUDPC in some of the resistant lines did not correspond to a lower 'r' value. Most of the resistant lines were derived from Seri, Myna, Bau, kauz, Hork 's' and Aegilops tauschii Coss.
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  • 39
    ISSN: 1573-6857
    Keywords: alcoholic resources ; Drosophila ; habitat selection ; Indian subcontinent ; short range variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In five Indian localities, it was possible to collect D. melanogaster in two different types of habitats, namely ordinary domestic and alcohol rich ones. Tolerance and utilization capacity of several alcohols and of acetic acid were analyzed in a total of 10 local populations. Results on two other species (D. repleta and D. immigrans) were also available from one place. In each locality, the population from alcohol rich habitat proved to be more tolerant to all the investigated products and also to be more capable of using them as a resource. Alcohols toxicity increased with increasing carbon chain length and secondary alcohols were more toxic than primary ones. Utilization capacity of all products was relatively independent of their toxicity. Especially acetic acid, the toxicity of which was low and similar to that of ethanol, was always a fairly poor resource. From a genetic point of view, tolerance and utilization capacity appeared as two relatively independent traits. Natural selection, which is responsible for the genetic differentiation of local populations, is likely to act simultaneously on both traits.
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    Genetica 107 (1999), S. 103-111 
    ISSN: 1573-6857
    Keywords: Drosophila ; genome evolution ; model organisms ; transposons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Model organisms have proved to be highly informative for many types of genetic studies involving ‘conventional’ genes. The results have often been successfully generalized to other closely related organisms and also, perhaps surprisingly frequently, to more distantly related organisms. Because of the wealth of previous knowledge and their availability and convenience, model organisms were often the species of choice for many of the earlier studies of transposable elements. The question arises whether the results of genetic studies of transposable elements in model organisms can be extrapolated in the same ways as those of conventional genes? A number of observations suggest that special care needs to be taken in generalizing the results from model organisms to other species. A hallmark of many transposable elements is their ability to amplify rapidly in species genomes. Rapid spread of a newly invaded element throughout a species range has also been demonstrated. The types and genomic copy numbers of transposable elements have been shown to differ greatly between some closely related species. Horizontal transfer of transposable elements appears to be more frequent than for nonmobile genes. Furthermore, the population structure of some model organisms has been subject to drastic recent changes that may have some bearing on their transposable element genomic complements. In order to initiate discussion of this question, several case studies of transposable elements in well-studied Drosophila species are presented.
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    Genetica 107 (1999), S. 95-102 
    ISSN: 1573-6857
    Keywords: Drosophila ; genomic regulation ; telomeric activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The structural integrity of TART elements has been used as reporter of instability at chromosomal ends in numerous Drosophila stocks and over time in an unstable stock. The results show that telomeric activity is a regulated process that may differ between the stocks as well as over time within a stock.
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    Chromosome research 7 (1999), S. 449-460 
    ISSN: 1573-6849
    Keywords: Apis ; Bombyx ; Drosophila ; Ephestia ; fluorescence in-situ hybridization (FISH) ; Galleria ; Gammarus ; insect phylogeny ; Ips ; Locusta ; Megaselia ; Pyrrhocoris ; Southern hybridization ; Tegenaria ; telomere ; Tenebrio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We studied the occurrence of the TTAGG telomere repeats by fluorescence in-situ hybridization (FISH) and Southern hybridization in ten insect species and two other arthropods. (TTAGG)n-containing telomeres were found in three Lepidoptera species, the silkworm Bombyx mori (in which the telomeric sequence was recently discovered), the flour moth Ephestia kuehniella, and the wax moth Galleria mellonella, in one species of Hymenoptera, the honey bee Apis mellifera, in one species of Coleoptera, the bark beetle Ips typographus, in one species of Orthoptera, the locust Locusta migratoria, and in a crustacean, the amphipod Gammarus pulex. They were absent in another species of Coleoptera, the mealworm Tenebrio molitor, two representatives of Diptera, Drosophila melanogaster and Megaselia scalaris, a species of Heteroptera, the bug Pyrrhocoris apterus and a spider, Tegenaria ferruginea. Our results, which confirm and extend earlier observations, suggest that (TTAGG)n was a phylogenetically ancestral telomere motif in the insect lineage but was lost independently in different groups, being replaced probably by other telomere motifs. In the Coleoptera this must have happened rather recently as even members of the same family, Curculionidae, differ with respect to the telomeric DNA.
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  • 43
    ISSN: 1573-6857
    Keywords: Drosophila ; nasuta-albomicans ; complex ; cytoraces ; body size ; fertility ; ovariole number ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Our long range interracial hybridization experiments between a pair of cross fertile races, Drosophila nasuta (2n = 8) and D.albomicans (2n = 6) have resulted in the evolution of two new karyotypic strains under laboratory conditions, which are named as Cytorace 1 and Cytorace 2. These Cytoraces harbor chromosomes from both parents. Here, we compare the body size of the parental races and newly evolved Cytoraces and the relationship between the body size and fitness. Analysis reveals that the parental races have reduced fertility and are larger in body size than newly evolved Cytoraces. Thus, the newly evolved Cytoraces show reduced body size and better fitness in the course of their evolution.
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  • 44
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    Photosynthesis research 59 (1999), S. 1-7 
    ISSN: 1573-5079
    Keywords: leaf gas exchange ; ozone ; Pisum sativum ; Rubisco ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previous studies have shown that short exposure of plants to high doses of ozone decreases subsequent photosynthesis; initially by reducing carboxylation capacity. This study tests the hypothesis that this is also the primary cause of loss of photosynthetic capacity in leaves affected by development under a low level of ozone. Triticum aestivum and Pisum sativum plants were exposed from germination to ozone in air (80 nmol mol-1 for 7 hours per day, for 18 days. Leaves that had completed lamina expansion at this time were free of visible injury and light absorptance was unaffected. However, some significant changes in photosynthetic gas exchange were evident. Photosynthetic CO2 uptake at light saturation was decreased significantly by 35% in T. aestivum but was unchanged in P. sativum. The reduction in photosynthesis of T. aestivum was accompanied by a 31% decline in the maximum velocity of carboxylation measured in vivo. Decreased stomatal conductance did not contribute to this reduction of photosynthesis because there was no significant change in the stomatal limitation to CO2. Processes directly dependent upon photochemical reactions; that is, the quantum yield of CO2 uptake and capacity for regeneration of ribulose 1,5-bisphosphate were not affected by O3 fumigation in either species. This suggests that for wheat, the quantitative cause of decreased photosynthetic rate in vivo is a decrease in the quantity of active ribulose-1,5- bisphosphate carboxylase-oxygenase.
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  • 45
    ISSN: 1573-1561
    Keywords: Aphid ; experience ; probing behavior ; sieve elements ; salivation ; cell punctures ; hydroxamic acids ; EPG ; Sitobion fragariae ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We hypothesized that aphids after previous exposure to hydroxamic acids (Hx), a family of secondary plant compounds deleterious to aphids, are able to reduce their subsequent exposure to them. This hypothesis was tested by evaluating the time to produce salivation into a sieve element (SSE) by the aphid Sitobion fragariae on seedlings of two wheat cultivars of Triticum aestivum differing in their concentration of Hx. The total time to produce a first SSE was significantly longer in the high-Hx cultivar; however, the subsequent, second SSE (first SSE after interruption of probing) in this cultivar was significantly reduced, reaching the level observed in the low-Hx plants. Therefore, a strategy to reduce the exposure to secondary compounds was observed only in the second SSE in high-Hx plants. When the experimental plant was replaced by a new unattacked plant after the first SSE, aphids did not change the behavior described, thus excluding an aphid-induced plant susceptibility. The number of cell punctures and accumulated duration was not affected by previous exposure to Hx, either in low or high Hx cultivars. Total time and pathway time but not cell punctures, seem to be the variables affected by previous exposure to Hx.
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  • 46
    ISSN: 1573-0867
    Keywords: bicarbonate-extractable soil phosphorus ; Lupinus angustifolius ; residual value ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Decreases in Colwell bicarbonate soil test P in the years after applying single (ordinary) superphosphate, and the residual value of superphosphate, was measured in a long-term field experiment on a duplex (texture contrast) soil (sand over lateritic ironstone gravel clay sand at 10–15 cm), at Wongan Hills, Western Australia, typical of many soils used to grow crops in Western Australia. Ten levels of P (0–91 kg P ha-1) were applied once only in late May to different plots in different years from 1988 to 1993. Wheat (Triticum aestivum), or lupin ( Lupinus angustifolius)) were sown in late May of each year, when the P treatments applied that year were banded (drilled) with the seed. Soil samples were collected each June to measure soil test P. Seed (grain) yields of the crops were measured each December. The residual value (RV) of P applied in previous years was calculated relative to P applied in the current year, using grain yields (RVyield) and soil test P (RVsoil). Soil test P measured on soil samples collected in June was related to yields measured in December that year to provide soil P test calibrations. Relative to P applied in the current year, soil test P decreased by between 15 to 30% for P applied one year previously, by 25 to 30% for P applied three years previously, and by 60 to 70% for P applied six years previously. Soil test P was affected by spatial variation, and it also varied in the different years, for P applied in the current year, one year previously, two years previously, etc. Compared with P applied in the current year, mean RVyield determined in the different years decreased by about 40% one year after P application, followed by a further 20% decrease for P applied two years previously, followed by a further 20% decrease for P applied three to five years previously. Relative to current P, RVsoil decreased by about 25% one year after P application, followed by a further 20% for P applied two years previously, followed by a further 10% for P applied three years ago, and followed by a further 6% for P applied four and five years ago. As measured in the different years, the soil P test calibration varied between years for P applied one, two etc. years previously. This was so even when the same cultivar of wheat was grown at the same site in different years.
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  • 47
    ISSN: 1573-5087
    Keywords: flooding ; kinetin ; leaf relative water content ; membrane stability ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Wheat plants, 22d. old, were exposed to wide range of soil water osmotic potential (Ψs = 0 to −1.2 MPa) induced by NaCl and CaCl2 treatments in combination with roots maintained under aerobic (drained at field capacity) or nonaerobic (flooded) conditions in the soil, and sprayed with 10 mg L−1 kinetin solution. In drained plants, not receiving kinetin, increased soil salinity resulted in appreciable inhibition of shoot growth and reduction in chlorophyll (Ch1.), soluble sugars (SS) contents and grain yield. Shoot growth, Ch1. content, soluble sugars and grain yield were significantly lower for flooded plants than unflooded analogues over the entire Ψs range. Both salinity and waterlogging synergize to increase Na+, Ca+ and Cl− accumulation in shoot tissues and to decrease the stability of leaf membranes to either dehydration (40% polyethylene glycol 6000) or heat (51 °C) stress. The ratio of K+/Na+ transported to shoots under aerobic and anaerobic conditions decreased progressively on salinization. The association between the internal mineral element concentrations was largely affected by kinetin treatment. Kinetin application ameliorated the deleterious effects of salinity and oxygen deficiency. It reduced Na+, Ca2+ and Cl− accumulation and improved K+ uptake under salinity and waterlogging stresses. Increased K+/Na+ ratio helped the plants to avoid Na+ toxicity and enhanced shoot growth and grain yield. Kinetin also reduced membrane injury by dehydration and heat stresses and improved the water status of plants under both aerobic and anaerobic conditions. The effects of single factors (Soil salinity ‘Ψs’, soil waterlogging ‘WL’ and Kinetin ‘Kin’) and their interactions (Ψs × WL, Ψs × Kin, WL × Kin and Ψs × WL × Kin) were shown by analysis of variance to be statistically significant for most parameters tested. Calculation of the coefficient of determination (η+) led to three important findings. (1) Salinity (Ψs) was dominant in affecting leaf relative water content (RWC), shoot dry mass, grain yield, stability of leaf membranes to dehydration stress and the contents of Na+, Ca2+, Mg2+ and Cl−. (2) Kinetin (Kin) had a dominant effect on the stability of leaf membranes to heat stress as well as on chlorophyll and soluble sugars contents. (3) The share of waterlogging (WL) was dominant for K+ content. It can be concluded that kinetin application helped wheat plants to grow successfully in the areas subjected to combined effects of salinity and oxygen deficiency, such as in salt marshes.
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  • 48
    ISSN: 1573-5109
    Keywords: Aegilops tauschii ; hairy auricles ; hairy leaf sheath ; inheritance ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Inheritance of genes for hairy auricles and hairy leaf sheath of Ae. tauschii in hexaploid wheat backgrounds (synthetic hexaploid wheat and common wheat varieties) was analyzed. The results indicated that hairy auricles and hairy leaf sheath of Ae. tauschii can be transferred and are expressed in hexaploid wheat. In a synthetic hexaploid wheat ('Ae. tauschii' 188) hairy auricles was proved to be controlled by a single dominant gene derived from Ae. tauschii, which was different from the Pa gene located on chromosome 4BS of common wheat. The hairy leaf sheath phenotype of 'Altar 84/Ae. tauschii 188' was also controlled by a single dominant gene derived from Ae. tauschii, which is obviously different from the Hls gene in T. dicoccoides. We suggest to designate the Ae. tauschii genes for hairy auricles and hairy leaf sheath as Pa2 and Hls2, respectively; such genes could be used as useful genetic markers in common wheat.
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  • 49
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    Plant cell, tissue and organ culture 59 (1999), S. 151-154 
    ISSN: 1573-5044
    Keywords: Ne1 ; Ne2 ; necrotic hybrid ; Triticum aestivum ; viable seeds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hybrid necrosis in wheat is a problem for gene transfer in wheat breeding. Hybrid necrosis occurs due to dominant complementary interaction of two genes, Ne1 and Ne2. A cross between wheat (Triticum aestivum L.) varieties C306 (drought tolerant, Ne1 carrier) and WL711(high yielding, Ne2 carrier) produced necrotic F1 hybrids, which died before ear emergence and produced no seeds. To overcome the problem of hybrid necrosis, ears enclosed in the leaf sheath were taken and cultured to maturity in liquid medium containing 5% sucrose and 0.04% glutamine. The necrotic hybrids produced only a few seeds per ear compared to parents, but individual grain weight was similar in the hybrid and the parents. The F1 ear culture study has been repeated for three years and F2 seeds obtained. In 1996–97, the cultured ears of F1 hybrids produced 62 seeds, of which only 52 showed germination and were grown under normal field conditions. Out of the 52 seeds, 50% were non-necrotic and showed segregation for various physiological traits. The results reveal that hybrids ears had the potential to form viable seeds. Culturing of wheat ears before ear emergence and production of viable F2 seeds from necrotic hybrids is a simple and efficient method for overcoming the problem of hybrid necrosis.
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  • 50
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    Euphytica 105 (1999), S. 125-131 
    ISSN: 1573-5060
    Keywords: disease resistance ; inheritance ; Karnal bunt ; Neovossia ; Tilletia indica ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Inheritance of resistance to Neovossia indica was studied in a Triticum aestivum line HD 29. To overcome the influence of environment on disease expression, the study was conducted by extensive evaluation of advanced generation (F8) recombinant inbred lines (RILs) developed by single seed descent from the cross WL 711 (susceptible) × HD 29 (resistant. The results suggested that HD 29 possesses three major genes for resistance to isolated Ni7 and two genes for resistance to isolate Ni8. One of the two genes controlling resistance to Ni8 is common with one of the genes conferring resistance to Ni7. These observations have important implications in breeding for Karnal bunt resistance.
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  • 51
    ISSN: 1573-5060
    Keywords: C-banding ; chromosome additions ; chromosome substitution ; Elymus tsukushiense ; homoeology ; in situ hybridization ; RFLP ; Roegneria kamoji ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Elymus tsukushiense Honda (syn. Roegneria kamoji C. Koch) (2n = 6x = 42, StsStsHtsHtsYtsYts) is a hexaploid species, distantly related to bread wheat Triticum aestivum L. em Thell (2n = 6x = 42, AABBDD). Apart from the delineation of evolutionary relationships, this species is a potential source of resistance to scab, a devastating disease of wheat caused by Fusarium graminearum Schw. A standard C-banded karyotype was established identifying all 21 chromosome pairs of E. tsukushiense. By using C-banding and genomic in situ hybridization analyses, three wheat-E. tsukushiense chromosome addition lines, one ditelosomic addition line, and one disomic substitution line were identified in BC2 progenies from wheat × E. tsukushiense hybrids. Twenty DNA markers specific for the seven homoeologous groups of the Triticeae were used to determine the homoeology of the added E. tsukushiense chromosomes. The E. tsukushiense chromosomes in the addition lines NAU702, NAU703, and NAU701 were identified as belonging to homoeologous groups 1, 3, and 5, and thus, were designated as 1Ets#1, 3Ets#1, and 5Ets#1, respectively. NAU751 was identified as a disomic substitution line with chromosome 3A of wheat replaced by chromosome 3Ets#1. Line NAU702 has a high level of resistance to scab and will be used in chromosomal engineering and development of improved wheat germplasm for scab resistance breeding.
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  • 52
    ISSN: 1573-5060
    Keywords: 1BL/1RS ; bread-making quality ; prolamins ; wheat-rye translocations ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The allelic variation of prolamin loci was studied in three F2 progenies from three crosses between the 1BL/1RS cultivar Triana and Yécora Rojo, Pavón and Florence Aurora, cultivars without the translocation. According to the 1:2:1 theoretical proportions observed in the allelic variants of the Glu-B3/Gli-B1 loci of the parent without the translocation, the inheritance as a block of the rye chromosome arm was confirmed. A group of F3-F4 recombinant lines, developed from these crosses was evaluated using the SDS-sedimentation test and the mixograph and alveograph tests. The presence of the 1BL/1RS translocation was not associated with significantly lower grain protein content values or with the optimum mixing time in the mixograph of the genotypes. The effect of the 1BL/1RS translocation on most of the quality parameters was highly dependent on the genetic pool. Significant increases in gluten strength and better mixing properties associated with the presence of some alleles of the Glu-A1, Glu-A3/ Gli-A1 and Gli-D2 loci were detected. The additivity and the interaction of prolamin gene effects with the rye translocation in the 1BL/1RS lines and its possible use in plant breeding are discussed.
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  • 53
    ISSN: 1573-5060
    Keywords: Blumeria graminis ; powdery mildew ; QTL ; RFLPs ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A segregating population of doubled-haploid lines issued from the cross between the wheat (Triticum aestivum L. em. Thell) cultivars Courtot, resistant to several isolates of powdery mildew (Blumeria graminis DC. f. sp. tritici Em. Marchal), and Chinese Spring (susceptible) was used to map Mlar, a gene carried by Courtot and conferring resistance to this pathogen. The assignation of Mlar using monosomic lines of Courtot was confirmed by the mapping analysis. Mlar was located on the short arm of the chromosome 1A, in the vicinity of the locus XGli-A5 coding for storage proteins. This result was in accordance with those demonstrating that Mlar was an allele of the Pm3 locus (Pm3g), a gene also involved in the resistance to powdery mildew.
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  • 54
    ISSN: 1573-5060
    Keywords: disease assessment ; maturity ; resistance ; Septoria tritici ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nineteen cultivars, with large differences in heading date, were evaluated for their response to septoria tritici blotch in two experimental setups in Njoro, Kenya. Due to the more or less constant temperatures during the growing season and the overhead irrigation applied the epidemic conditions were similar over the whole observation period for the early and late cultivars. In experiment 1 the cultivars were assessed for disease severity at the same moment irrespective of the developmental stage, while in experiment 2 the cultivars were assessed at the same developmental stage. Measured at the same time, the disease severity was highest in the early maturing cultivars and lowest in the late maturing cultivars (r = –0.78). When assessed at the same development stage the disease build up was independent of heading date (r = –0.10) but strongly dependent on resistance level. There were no indications that early heading cultivars were more susceptible than late heading cultivars.
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  • 55
    ISSN: 1573-5060
    Keywords: allelic variation ; glutenin subunit ; Japanese Norin variety ; seed storage protein ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seed storage proteins of 131 Japanese Norin wheat (Triticum aestivum) varieties were fractionated by sodium dodecyl sulfate polyacrylamide gel electrophoresis to determine allelic make-up in varieties at each of three loci that control high-molecular-weight (HMW) glutenin subunits. Three alleles were identified at the Glu-A1 locus, six at the Glu-B1 locus and five at the Glu-D1 locus. Twenty-four different, major glutenin HMW subunits were identified and each contained three to five subunits and seventeen different glutenin subunit patterns were observed for 19 subunits in the 131 Japanese Norin varieties. Fourteen alleles were identified by comparison of subunit mobility with that previously found in hexaploid wheat. Japanese Norin varieties showed a specific pattern of allelic variation in glutenin HMW subunits, different from that of Chinese and other country common wheats in allelic frequency at Glu-1 loci.
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  • 56
    ISSN: 1573-5036
    Keywords: boron ; genotypic difference ; sterility ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two pot experiments at the Plant Environment Laboratory (PEL), Reading, UK investigated sterility, boron (B) accumulation and B partitioning of wheat cultivars grown with limited B in the growing medium. The first experiment evaluated nine cultivars of spring wheat with diverse field responses to low available soil B, supplied with or without 20 μM B. A second experiment examined the response of a susceptible (SW-41) and a tolerant (Fang-60) cultivar to B-deficiency. These cultivars were supplied with either 20 μM B from sowing to flag leaf emergence and no added B thereafter, or 20 μM B from sowing to maturity. When B was not supplied in the nutrient solution, the number of grains ranged from 4 per ear (cv. BL-1135) to 32 per ear (cv. BL-1249) and sterility of competent florets ranged from 39% to 93%. Boron concentration in the flag leaf at anthesis did not differ greatly when the growing medium contained limited B, but differences between cultivars were evident when B was unlimited. Tolerance of B-deficiency was not related to the B concentration in the flag leaf. Some cultivars produced viable pollen and set grains while others failed to do so at similar B concentrations in the flag leaf. The two contrasting cultivars did not differ much in their pattern of B partitioning when B supply was restricted from flag leaf emergence onwards. Similarly, little evidence was found that the tolerant cultivars translocated B from their leaves, roots or stems when the supply in the growing medium was restricted. The proportion of total B partitioned in different organs was the same irrespective of B supply and cultivar. On average, leaves contained 68% of the total B content in the whole plant compared to 16% in the roots, 10% in the ears and only 6% in the stems. Tolerant or susceptible cultivars of wheat could not be distinguished based on the B concentration and B content of the flag leaf.
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  • 57
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    Plant cell, tissue and organ culture 57 (1999), S. 207-210 
    ISSN: 1573-5044
    Keywords: biolistics ; gene expression ; haploid ; transformation ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using the PDS-1000/He Biolistic® Particle Delivery System, the microprojectile travel distance, rupture disk pressure and DNA/gold particle concentrations were assessed in order to optimise short and longer-term β-glucuronidase reporter gene expression in microspore-derived embryos of wheat. The effects were also evaluated of using sterile filter paper to support explants and treatment with a high osmoticum medium (0.2 M mannitol/0.2 M sorbitol or 0.4 M maltose). In the optimised procedure, wheat microspore-derived embryos (MDEs), were placed on filter paper and incubated on medium containing 0.4 M maltose, for 4 h pre- and 45 h post-bombardment. Five μl pAHC25 (0.75 mg ml-1 in TE buffer) was precipitated onto 25 μl gold particles (60 mg ml-1 in sterile water), using 20 μl spermidine (0.1 M) and 50 μl CaCl2 (2.5 M). The particles were centrifuged and resuspended in 75 μl absolute ethanol prior to the preparation of 6 macrocarriers. A microprojectile travel distance of 70 mm, a rupture pressure of 1300 p.s.i., and a vacuum of 29′′ Hg were employed. Maltose at 0.4 M in the support medium was the most important factor influencing GUS activity in bombarded tissues. GUS activity, 1 day post-bombardment, reached 52 ± 17 GUS-positive foci/MDE (mean ± s.e.m, n=3), with 17 ± 4 foci/MDE at 15 days, giving a 3.0-fold increase (p〈0.05) compared to expression in MDEs bombarded on medium without a high osmoticum treatment.
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  • 58
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    Chromosome research 7 (1999), S. 445-448 
    ISSN: 1573-6849
    Keywords: chromosomes ; cytological technique ; Drosophila ; embryos ; mitosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 59
    ISSN: 1573-6857
    Keywords: Drosophila ; heritability ; principal component analysis ; shape ; size
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract ‘Traditional morphometrics’ allows us to decompose morphological variation into its major independent sources, identifying them usually as size and shape. To compare and investigate the properties of size and shape in natural populations of Drosophila mediopunctata, estimating their heritabilities and analysing their temporal and microgeographic changes, we carried out collections on seven occasions in Parque Nacional do Itatiaia, Brazil. In one of these collections, we took samples from five different altitudes. Measurements were taken from wild caught inseminated females and up to three of their laboratory‐reared daughters. Through a principal component analysis, three major sources of variation were identified as due to size (the first one) and shape (the remaining two). The overall amount of variation among laboratory flies was about half of that observed among wild flies and this reduction was primarily due to size. Shape variation was about the same under natural and artificial conditions. A genetic altitudinal cline was detected for size and shape, although altitude explained only a small part of their variation. Differences among collections were detected both for size and shape in wild and laboratory flies, but no simple pattern emerged. Shape variation had high heritability in nature, close to or above 40% and did not vary significantly temporally. Although on the overall size heritability (18 ± 6%)was significant its estimates were not consistent along months – they were non‐significant in all but one month, when it reached a value of 51 ± 11%. Overall, this suggests that size and shape have different genetic properties.
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  • 60
    ISSN: 1573-9058
    Keywords: diurnal variation ; photoinhibition ; photosystem 2 reaction centres ; state transition ; trans-thylakoid membrane proton gradient ; Triticum aestivum ; xanthophyll cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Non-photochemical quenching of chlorophyll fluorescence (qN) and its three components (qNf, qNm, and qNs) in the flag leaves of wheat grown in the field were studied by a fluorometer PAM-2000 on clear days. The diurnal variation patterns of qN in just fully extended (JFEL) and aging leaves (AL) were similar, but qNm declined markedly in JFEL while it remained at a relatively high level in AL under strong sunlight at noon. Furthermore, at midday qNf was higher than qNs in JFEL, but much lower in AL. The results show the relative contributions of different mechanisms in preventing the photosynthetic apparatus from photodamage change during leaf development.
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  • 61
    ISSN: 1573-9058
    Keywords: D1 protein ; diphenylcarbazide ; oxygen evolving complex ; scavengers ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Irradiation of thylakoid membranes at 40 °C resulted in complete inhibition of photosystem (PS) 2 activity measured as 2,6-dichlorophenol indophenol (DCIP) photoreduction either in the absence or presence of 1,5-diphenylcarbazide (DPC). Concomitant with the inactivation of PS2 activity, several thylakoid proteins were lost and high molecular mass cross-linking products appeared that cross-reacted with antibodies against proteins of PS2 but not with antibodies against proteins of other three complexes PS1, ATP synthase, and cytochrome b6f. Irradiation of thylakoid membranes suspended in buffer of basic pH or high concentration of Tris at 25 °C resulted in the formation of cross-linking products similar to those in thylakoid membranes irradiated at 40 °C. Presence of radical scavengers and DPC during the high temperature treatment prevented the formation of cross-linking products. These results suggest the involvement of oxygen evolving co mplex (OEC) in the formation of cross-linking between PS2 proteins in thylakoid membrane irradiated at high temperature.
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  • 62
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    Photosynthetica 36 (1999), S. 433-440 
    ISSN: 1573-9058
    Keywords: antibody ; polyacrylamide gel electrophoresis ; protease ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Exposure of thylakoid membranes to high temperature in dark leads to the degradation of D1 protein. Maximum degradation of D1 protein occurred at 45 °C. Using N-terminal specific D1 antibody, a 23 kDa fragment of D1 protein was detected. The degradation of D1 protein could be prevented both by radical scavengers and inhibitors of serine protease and metallo-protease. These results suggest that degradation of D1 protein during exposure of thylakoid membranes to high temperature in dark is catalyzed by protease.
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  • 63
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    World journal of microbiology and biotechnology 15 (1999), S. 417-423 
    ISSN: 1573-0972
    Keywords: 15N ; nitrogen mineralization ; Pseudomonas fluorescens ; rhizosphere ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The effects of an antibiotic-producing Pseudomonas fluorescens strain (F113) carrying the marker gene cassette lacZY and a marked, non-producing strain (F113G22) on the uptake of nitrogen from 15N-enriched organic residues incorporated into a sandy soil were investigated in microcosm studies. Strain F113 produces the antibiotic 2,4-diacetylphloroglucinol (DAPG), whilst its modified derivative strain F113G22 has DAPG production deleted by Tn5 mutagenesis. Uptake of nitrogen by wheat (Triticum aestivum) from 15N-enriched organic residues was estimated using stable isotope-ratio mass spectrometry of shoot and root material of 17-day-old plants. In addition, plant growth and active microbial biomass in soil were monitored. In contrast to results obtained in our previous study on pea (Pisum sativum), it was found that in wheat, inoculation with either strain F113 or F113G22 decreased the proportion of nitrogen derived from 15N-labelled organic residues incorporated into soil as compared to non-inoculated controls. It is therefore suggested that these strains decreased mineralization of organic residues in the rhizosphere of wheat, making less inorganic N (15N) available for plant uptake. The results of this study indicate that the effects of introduced Pseudomonas fluorescens strains on nitrogen mineralization in the rhizosphere are plant-species dependent, and highlight the importance of testing microbial inocula on a range of plant species.
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  • 64
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    Behavior genetics 29 (1999), S. 65-73 
    ISSN: 1573-3297
    Keywords: Mating behavior ; reproductive isolation ; sexual isolation ; sibling species ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract In an investigation into the effects of developmental isolation from all conspecifics, the Drosophila willistoni group of six sibling species responded to differing degrees: all six are reproductively isolated from D. paulistorum, the tester species. Drosophila pavlovskiana, a narrow endemic, proved the most vulnerable, responding by reducing its adult sexual isolation, if eggs, any instar, and sometimes even pupae were socially isolated. To lesser degrees, D. tropicalis and D. willistoni both produced similar results only when their eggs were isolated, i.e., when from the moment of egg deposition on, there was absolutely no contact with other flies until testing for mating behavior. The remaining siblings, D. equinoxialis and D. insularis, were immovable.
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  • 65
    ISSN: 1573-3297
    Keywords: Drosophila ; oviposition-site preference ; alcohol dehydrogenase ; transgene coplacement ; ethanol
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    Topics: Biology , Psychology
    Notes: Abstract The preference of Drosophila females to lay eggs on substrates that do or do not contain alcohol is an excellent system to study the evolutionary genetics of behavior, because (1) there is variation in this behavior within and among species, (2) the behavior is amenable to laboratory investigation, and (3) the behavior presumably has a direct relationship to reproductive fitness. Moreover, a key genetic component of the system, the Alcohol dehydrogenase (Adh) locus, is arguably the most well characterized gene known. However, because the Adh gene and its genetic background are inseparable in reproductively isolated species, it is difficult to establish its role in behavioral divergence. By transgene coplacement, we created pairs of strains of D. melanogaster expressing an Adh allele from either D. melanogaster or D. affinidisjuncta, a Hawaiian species with very low levels of ADH in adults. When raised on ethanol-containing medium, the affinidisjuncta–Adh strains experience high mortality relative to the melanogaster–Adh strains. However, affinidisjuncta–Adh females show the same preference for oviposition on ethanol-containing medium as melanogaster–Adh females. Thus, preference for ethanol in these strains is not determined primarily by Adh genotype.
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  • 66
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    European journal of plant pathology 105 (1999), S. 917-925 
    ISSN: 1573-8469
    Keywords: ergosterol ; detached glumes ; interaction ; Mycosphaerella graminicola ; Phaeosphaeria nodorum ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Interactions between Stagonospora nodorum and Septoria tritici were studied. Results from a detached glume experiment indicated that the interaction may be isolate-dependent, as it was shown that the interaction between the two pathogens may be beneficial or antagonistic depending on the isolate of each pathogen present. The number of spores produced by both pathogens was significantly greater when an aggressive isolate of S. tritici was mixed with a non-aggressive isolate of S. nodorum, whereas the number of spores produced by both pathogens was significantly less when two non-aggressive isolates were mixed. There was a significant reduction in disease level when S. tritici was applied prior to S. nodorum, compared to vice versa in the growth chamber. Results from growth chamber and field studies showed that S. nodorum produced significantly more spores when both pathogens were present together. It is concluded that S. tritici has a stimulatory effect on spore production by S. nodorum. However, there was a reduction of S. tritici spores observed in the dual inoculation treatments, suggesting that S. nodorum inhibits S. tritici.
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  • 67
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    Evolutionary ecology 13 (1999), S. 211-220 
    ISSN: 1573-8477
    Keywords: Drosophila ; evolutionary genetics ; host specificity ; parasitoid ; virulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The developmental success of Leptopilina boulardi parasitoids within host species of the melanogaster subgroup is determined mainly by their ability to suppress the host immune reaction (virulence). Host resistance and parasitoid virulence are genetically variable in both partners. A gene for specific resistance against L. boulardi (Rlb) has been identified in Drosophila melanogaster, and a gene for the immune suppression (IS) of D. melanogaster has been identified in L. boulardi. To understand the evolution of the IS gene, we determined its specificity regarding potential hosts of the melanogaster subgroup. It did not affect the virulence against any other species of the melanogaster subgroup and was called ISm for immune suppression of D. melanogaster. Another gene (ISy), non-linked to the gene ISm, was characterized for the specific immune suppression of D. yakuba. These results suggesting that natural selection for virulence against one host species does not influence the evolution of virulence against another will allow us to develop pertinent hypotheses concerning the evolution of this character which is expected to drive the evolution of the parasitoid toward narrow host specialization.
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  • 68
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    Biologia plantarum 42 (1999), S. 217-222 
    ISSN: 1573-8264
    Keywords: chlorophyll ; photochemical activity ; photosystem 2 ; ribulose-1,5-bisphosphate carboxylase/oxygenase ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chlorophyll (Chl) a and b content, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) content and activity, and electron transport rate were measured in flag leaves of wheat genotypes Uniculm and Kalyansona, grown at suboptimal and optimal supply of nitrogen. The Chl content, RuBPCO activity, and electron transport rate were decreased due to suboptimal nitrogen supply only in Kalyansona. There was no change in the ratio of RuBPCO and photosystem 2 (PS2) activity at various stages which suggests that there was no alteration in distribution of N due to additional N supply.
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  • 69
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    Biologia plantarum 42 (1999), S. 119-123 
    ISSN: 1573-8264
    Keywords: anatomy ; epidermis ; heavy metals ; mesophyll ; Triticum aestivum ; vascular bundles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of 1 mM cadmium, lead and nickel on dry mass, Cd, Pb, and Ni contents, and changes in leaf structure in young wheat plants were studied. In leaves, Cd content was highest, followed by Pb and Ni, in roots Cd content was also highest, but followed by Ni and Pb. Roots accumulated considerably larger amounts of the three heavy metals than leaves. Largest reductions of leaf and root mass were obtained with Cd. Pb and Ni effects were almost equal. Ni excess had a strong negative effect on mesophyll thickness, while Cd mostly reduced the number and size of vascular bundles and vessel diameter. High Pb reduced the diameter of vessels causing their different deformations.
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  • 70
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    Entomologia experimentalis et applicata 86 (1998), S. 13-24 
    ISSN: 1570-7458
    Keywords: Drosophila ; cytoplasmic incompatibility ; Wolbachia ; temperature ; antibiotics ; density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of high temperatures, antibiotics, nutrition and larval density on cytoplasmic incompatibility caused by a Wolbachia infection were investigated in Drosophila simulans. Exposure of larvae from an infected stock to moderate doses of tetracycline led to complete incompatibility when treated females were crossed to infected males; the same doses only caused a partial restoration of compatibility when treated males were crossed to uninfected females. In crosses with treated females, there was a strong correlation between dose effects on hatch rates and infection levels in embryos produced by these females. Ageing and rearing males at a high temperature led to increased compatibility. However, exposing infected females to a high temperature did not influence their compatibility with infected males. Male temperature effects depended on conditions experienced at the larval stage but not the pupal stage. Exposure to 25 °C reduced the density of Wolbachia in embryos compared with a 19 °C treatment. Low levels of nutrition led to increased compatibility, but no effect of larval crowding was detected. These findings show the ways environmental factors can influence the expression of cytoplasmic incompatibility and suggest that environmental effects may be mediated by bacterial density.
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  • 71
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    Journal of insect behavior 11 (1998), S. 691-712 
    ISSN: 1572-8889
    Keywords: cactus ; Drosophila ; geographic variation ; host preference behavior ; Sonoran Desert ; volatiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previous studies have suggested that all populations of cactophilic Drosophila mojavensis prefer pitaya agria cactus, Stenocereus gummosus, over all other potential hosts for feeding and breeding, including populations that inhabit areas where no agria grows. We sampled five geographically isolated populations of D. mojavensis from nature to assess host choice within and between populations. Host choice tests were performed in a laboratory “olfactometer” by allowing adult D. mojavensis to choose between plumes of synthetic volatile cocktails of two widespread host cacti. Overall, each population showed significant preference for agria volatiles with one exception: a mainland Sonora population that uses organ pipe cactus in nature exhibited preference for organ pipe volatiles, suggesting a possible shift in host preference. The degree of preference for agria volatiles was greatest in a population from southern California that use California barrel cactus as a host. Since southern Californian populations of D. mojavensis are thought to be derived from those in Baja California, preference for agria volatiles is considered a retained ancestral trait. Three populations from Baja California and mainland Mexico that use agria in the wild expressed lower, but similar preferences for agria volatiles. Because populations of D. mojavensis are ancestral to those in mainland Mexico, Arizona, and California, the shift from agria to alternate hosts has not been accompanied by strong changes in host preference behavior.
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  • 72
    ISSN: 1572-8889
    Keywords: courtship behavior ; songs ; sexual isolation ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four species of the Drosophila virilis group, D. montana, D. littoralis, D. lummei, and D. ezoana, occur sympatrically in several locations in northern Europe. Courtship interactions between the flies of the three first-mentioned species were observed at malt baits in Kemi, northern Finland, to find out how the flies of different species recognize conspecific individuals and how interspecific courtships differ from intraspecific ones in the wild. Intraspecific courtships (including females of different reproductive stages) and interspecific courtships were also videotaped and analyzed in laboratory. In the wild the males courted both conspecific and allospecific females, even though the species varied in how much the males were attracted to females of different species. Interspecific courtships usually broke off when the male touched the female or when the male and/or the female vibrated his/her wings, producing acoustic cues. In the laboratory males courted conspecific females irrespective of the reproductive stage of the female, even though the courtships directed toward immature and fertilized females usually included only orienting and touching (no licking and singing). D. littoralis, and very rarely D. montana and D. lummei, males courted also allospecific females. In the few interspecific courtships between these three species, where the male proceeded to singing, females responded to male singing by vibrating their wings. This ended the courtship. It is suggested that both the chemical cues affecting female attractivity and the acoustic signals of males and females, which are produced by wing vibration, function in maintaining sexual isolation between these three species.
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  • 73
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    BioMetals 11 (1998), S. 359-372 
    ISSN: 1572-8773
    Keywords: calcium ; EGF-domains ; cadherins ; integrins ; calmodulin ; cytoskeleton ; Drosophila
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The known roles for calcium-binding proteins in developmental signaling pathways are reviewed. Current information on the calcium-binding characteristics of three classes of cell-surface developmental signaling proteins (EGF-domain proteins, cadherins and integrins) is presented together with an overview of the intra-cellular pathways downstream of these surface receptors. The developmental roles delineated to date for the universal intracellular calcium sensor, calmodulin, and its targets, and for calcium-binding regulators of the cytoskeleton are also reviewed.© Kluwer Academic Publishers
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  • 74
    ISSN: 1572-8889
    Keywords: Drosophila ; courtship song ; behavior ; female choice ; sexual isolation
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    Topics: Biology
    Notes: Abstract The courtship behavior and the effects of courtship song in inter- and intraspecific crosses were studied in the four sympatric species of the Drosophila auraria complex: D. auraria, D. biauraria, D. subauraria, and D. triauraria. Orientation, tapping, and vibration (the repertoires of male courtship) were observed in both inter- and intraspecific crosses, suggesting that signals from heterospecific females were enough to elicit such male behaviors. The crossability tests with wingless or winged heterospecific males (tests for wing effects) revealed that winged heterospecific males copulated less than wingless ones in all four species but not all the pairwise cases. Since the crossability tests with aristaless females (deaf) or normal females showed essentially the same results as the tests for wing effects, we concluded that the sound produced by wing vibration plays an important role and that the wing movement itself is less important. These findings suggest that courtship songs are of great importance in mate discrimination and the sexual isolation between the species of this complex.
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  • 75
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    Development genes and evolution 208 (1998), S. 37-45 
    ISSN: 1432-041X
    Keywords: Key words wingless ; Wnt ; Drosophila ; Brain development ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We have studied the role of the wingless gene in embryonic brain development of Drosophila. wingless is expressed in a large domain in the anlage of the protocerebrum and also transiently in smaller domains in the anlagen of the deutocerebrum and tritocerebrum. Elimination of the wingless gene in null mutants has dramatic effects on the developing protocerebrum; although initially generated, approximately one half of the protocerebrum is deleted in wingless null mutants by apoptotic cell death at late embryonic stages. Using temperature sensitive mutants, a rescue of the mutant phenotype can be achieved by stage-specific expression of functional wingless protein during embryonic stages 9–10. This time period correlates with that of neuroblast specification but preceeds the generation and subsequent loss of protocerebral neurons. Ectopic wingless over-expression in gain-of-function mutants results in dramatically oversized CNS. We conclude that wingless is required for the development of the anterior protocerebral brain region in Drosophila. We propose that an important role of wingless in this part of the developing brain is the determination of neural cell fate.
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  • 76
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    Development genes and evolution 207 (1998), S. 535-541 
    ISSN: 1432-041X
    Keywords: Key words Histones ; Oogenesis ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A genomic fragment was cloned from a DNA library constructed from a Drosophila enhancer trap line in which reporter gene expression was observed at the anterior-most tip of the ovaries and testes. This genomic clone was identified as the L-repeat of the Drosophila melanogaster histone gene cluster. Northern blotting and in situ hybridisation to RNA in tissues with individual cDNAs and PCR-generated probes for each histone confirmed that gene expression was greatest at the anterior portion of each ovariole, in the germarium, and was also elevated in a few individual nurse cells and somatic follicle cells within the egg chamber during early developmental stages. Histone H1 and each of the core histones had a similar expression pattern which was correlated to cell division. Maternal stores of histone transcripts were also transported to the mature oocyte from the nurse cells at a later stage of oogenesis (stage 10), when virtually all the nurse cells contained high levels of histone transcripts. The results are consistent with expression of the somatic histone gene cluster during oogenesis as a co-ordinate unit. There does not seem to be a reduced level of somatic type H1 in the germ-line, as is observed in some other species. The relationship between the P[lacZ] expression pattern in the germarium and the overall expression of the histone cluster suggests there are specific regulatory elements for germ-line expression.
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  • 77
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    Development genes and evolution 207 (1998), S. 462-470 
    ISSN: 1432-041X
    Keywords: Key words Genetic variation ; Sevenless ; EGF receptor ; Drosophila ; Photoreceptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The signal transduction pathway controlling determination of the identity of the R7 photoreceptor in the Drosophila eye is shown to harbor high levels of naturally occurring genetic variation. The number of ectopic R7 cells induced by the dosage-sensitive Sev S11.1 transgene that encodes a mildly activated form of the Sevenless tyrosine kinase receptor is highly sensitive to the wild-type genetic background. Phenotypes range from complete suppression to massive overproduction of photoreceptors that exceeds reported effects of known single gene modifiers, and are to some extent sex-dependent. Signaling from the dominant gain-of-function Drosophila Epidermal Growth Factor Receptor (DER-Ellipse) mutations is also sensitive to the genetic backgrounds, but there is no correlation with the effects on Sev S11.1 . This implies that different genes and/or alleles modify the two activated receptor genotypes. The evolutionary significance of the existence of high levels of genetic variation in the absence of normal phenotypic variation is discussed.
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  • 78
    ISSN: 1573-4978
    Keywords: mitochondria ; Drosophila ; sea urchin ; ATP synthase ; embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Complementary DNAs encoding nuclear-coded mitochondrial ATP synthase subunit α of Drosophila melanogaster and Strongylocentrotus purpuratus were obtained by a combination of library screening and redundant PCR. The entire coding sequence of the precursor polypeptide was inferred for both species. Southern blots to genomic DNA indicated that the gene is almost certainly single-copy in both organisms. Northern blots to RNA from staged developmental series showed that ATP synthase subunit α mRNA is represented in the egg, declines in abundance during cleavage, and is replenished by zygotic transcription in both species. However, the extent and timing of these changes differ significantly in the two species studied. Nuclear-coded and mitochondrially encoded ATP synthase genes appear to be temporally co-regulated in Drosophila, but not sea urchin development.
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  • 79
    ISSN: 1432-203X
    Keywords: Key words Bread wheat ; Triticum aestivum ; Tritordeum ; Tissue electroporation ; Transient gene expression
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    Topics: Biology
    Notes: Abstract Wheat scutella and tritordeum inflorescences were transformed by tissue electroporation with plasmid DNA containing a β-glucuronidase (GUS) gene (gus A) under the control of the rice actin1 promoter. Factors affecting electroporation efficiency were analysed. Important factors were electroporation voltage and pulse length, the volume of electroporation buffer, the osmoticum of electroporation buffer and medium, the osmoticum of pre-electroporation culture medium, and pre-electroporation incubation time and temperature. Maximum transient gene expression was obtained with a single pulse of 550 V/cm from a 960-μF capacitor, using 200 μl of electroporation buffer, after 2–3 h culture on media with 357 mOsm for wheat scutella or 1 day on media with 222 mOsm for tritordeum inflorescences, and 0.5–1 h pre-electroporation incubation with DNA at 24 °C. Under these conditions, up to 90% of the explants showed GUS expression, and up to 149 expression signals were recorded per replicate. Electroporated explants showed high rates of survival and retained the ability to regenerate plants via somatic embryogenesis.
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  • 80
    ISSN: 1432-2242
    Keywords: Key words Aegilops markgrafii ; Triticum aestivum ; Addition lines ; Chromosome markers ; Homoeology ; Wheat ; Wheat microsatellites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We describe the use of wheat microsatellites for the discrimination of Aegilops markgrafii chromosomes. Twenty out of eighty eight wheat microsatellites (WMS) tested were able to distinguish Triticum aestivum-Ae. markgrafii addition lines. Six, three, three, one and six of 18 WMS can be used as markers for single Ae. markgrafii chromosomes B, C, D, F and G, respectively. Addition line A is not available but additional bands, appearing only in Ae. markgrafii and the T. aestivum-Ae. markgrafii amphiploid and not in any of the available addition lines, indicate that three WMS detect markers for Ae. markgrafii chromosomes A. Addition line E could not be detected by any of the WMS markers applied, although the 20 WMS represented all the homologous groups of wheat. All three WMS located on the short arm of group-2 chromosomes were located on Ae. markgrafii chromosome B; three of four WMS, located on the long arm of wheat group-2 chromosomes, were specific to Ae. markgrafii chromosome G and three of four WMS, specific to group-5 chromosomes, were markers for Ae. markgrafii chromosome C, indicating the homoeology of these wheat chromosome arms with the respective Ae. markgrafii chromosomes.
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  • 81
    ISSN: 1432-2242
    Keywords: Key words RFLP analysis ; Triticum aestivum ; Genetic diversity ; Genetic similarity estimates ; Cluster analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Restriction fragment length polymorphisms (RFLPs) have been used to characterise the genetic diversity of wheat (Triticum aestivum) germplasm. One hundred and twenty-four accessions comprising all major Australian wheat varieties and lines important for breeding purposes were assayed for RFLPs with clones of known genetic location and selected to give uniform genome coverage. The objectives of this study were to determine RFLP-based genetic similarity between accessions and to derive associations between agronomically significant traits and RFLP phenotypes. Ninety-eight probes screened against genomic DNA digested with five restriction endonucleases detected a total of 1968 polymorphic fragments. Genetic similarity (GS) calculated from the RFLP data ranged from 0.004 to 0.409 between accessions, with a mean of 0.18. Cluster analysis based on GS estimates produced four groupings that were generally consistent with available pedigree information. Comparisons of the RFLP phenotypes of accessions containing disease resistance genes present on introgressed alien segments enabled the identification of specific alleles characteristic of these regions. Associations were derived for a range of stem-rust, leaf-rust and yellow-rust resistance genes. These results suggest that RFLP analysis can be used for the characterisation and grouping of elite breeding material of wheat and RFLP profiling can identify chromosome segments associated with agronomic traits.
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  • 82
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    Theoretical and applied genetics 96 (1998), S. 69-75 
    ISSN: 1432-2242
    Keywords: Key words Aegilops umbellulata ; Co-linearity ; Comparative mapping ; Translocations ; Triticum aestivum ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A comparative genetic map of Aegilops umbellulata with wheat was constructed using RFLP probes that detect homoeoloci previously mapped in hexaploid bread wheat. All seven Ae. umbellulata chromosomes display one or more rearrangements relative to wheat. These structural changes are consistent with the sub-terminal morphology of chromosomes 2 U, 3 U, 6 U and 7 U. Comparison of the chromosomal locations assigned by mapping and those obtained by hybridization to wheat/Ae. umbellulata single chromosome addition lines verified the composition of the added Ae. umbellulata chromosomes and indicated that no further cytological rearrangements had taken place during the production of the alien-wheat aneuploid lines. Relationships between Ae. umbellulata and wheat chromosomes were confirmed, based on homoeology of the centromeric regions, for 1 U, 2 U, 3 U, 5 U and 7 U. However, homoeology of the centromeric regions of 4 U with wheat group-6 chromosomes and of 6 U with wheat group-4 chromosomes was also confirmed, suggesting that a re-naming of these chromosomes may be pertinent. The consequences of the rearrangements of the Ae. umbellulata genome relative to wheat for gene introgression are discussed.
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  • 83
    ISSN: 1432-2242
    Keywords: Key words Fluorescence in situ hybridization ; Translocation ; WSMV resistance ; Thinopyrum intermedium ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract   Thinopyrum intermedium is a promising source of resistance to wheat streak mosaic virus (WSMV), a devastating disease of wheat. Three wheat germplasm lines possessing resistance to WSMV, derived from Triticum aestivum×Th. intermedium crosses, are analyzed by C-banding and genomic in situ hybridization (GISH) to determine the amount and location of alien chromatin in the transfer lines. Line CI15092 was confirmed as a disomic substitution line in which wheat chromosome 4A was replaced by Th. intermedium chromosome 4Ai?2. The other two lines, CI17766 and A29-13-3, carry an identical Robertsonian translocation chromosome in which the complete short arm of chromosome 4Ai?2 was transferred to the long arm of wheat chromosome 4A. Fluorescence in situ hybridization (FISH) using ABD genomic DNA from wheat as a probe and S genomic DNA from Pseudoroegneria stipifolia as the blocker, and vice versa, revealed that the entire short arm of the translocation was derived from the short arm of chromosome 4Ai?2 and the breakpoint was located at the centromere. Chromosomal arm ratios (L/S) of 2.12 in CI17766 and 2.15 in A29-13-3 showed that the translocated chromosome is submetacentric. This translocated chromosome is designated as T4AL ⋅ 4Ai?2S as suggested by Friebe et al. (1991).
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  • 84
    ISSN: 1432-2242
    Keywords: Key words Triticum spelta ; Triticum aestivum ; SDS-PAGE ; Acid-PAGE ; Seed storage proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Seed storage proteins of a few selected spelt forms and crosses have already been electrophoretically analysed by SDS-PAGE and acid-PAGE and compared with a few winter wheat cultivars. In the analyses presented here further important Central European spelt varieties were included, as well as modern winter wheat cultivars which were chosen as standards. In this study gliadin and glutenin band patterns of modern Central European winter wheat cultivars were analysed, in particular for a comparison with spelt varieties. An improved differentiation within and between the two species was obtained.
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  • 85
    ISSN: 1432-2242
    Keywords: Key words Genetic diversity ; Triticum tauschii ; Triticum aestivum ; RFLP ; Landrace wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Chinese accessions of Triticum tauschii and T. aestivum L. from the Sichuan white (SW), Yunnan hulled (YH), Tibetan weedrace (TW), and Xinjiang rice (XR) wheat groups were subjected to RFLP analysis. T. tauschii and landraces of T. aestivum from countries in Southwest Asia were also evaluated. For T. tauschii, a west to east gradient was apparent where the Chinese accessions exhibited less diversity than those from Southwest Asia. Compared to the Southwest Asian gene pool, the Chinese T. tauschii was highly homogeneous giving a low frequency of polymorphic bands (16%) and banding patterns (1.33 per probe) with 75 RFLP probe-HindIII combinations. Accessions of T. tauschii from Afghanistan and Pakistan were genetically more similar to the Chinese T. tauschii than those from Iran. Of 368 bands found for 39 Chinese hexaploid wheat accessions with 63 RFLP probe-HindIII combinations, 28.3% were polymorphic with an average of 2.6 banding patterns per probe and 5.0 bands per genotype. The individual Chinese landrace wheat groups revealed less variation than those from Afghanistan, Iran, and Turkey. When classified into country based groups, however, the diversity level over all Chinese landraces was greater than that of some Southwest Asian landraces, especially those from Afghanistan and Iran . The XR wheat group was genetically distinct from the other three Chinese landrace groups and was more related to the Southwest Asian landraces. The TW group was genetically similar to, but more diverse than, the SW and YH groups. The Chinese landraces had a higher degree of genetic relatedness to the Southwest Asian T. tauschii, particularly to accessions from Iran, rather than to the Chinese T. tauschii. ‘Chinese Spring’ was most related to ‘Chengdu-guang-tou’, a cultivar from the SW wheat group.
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  • 86
    ISSN: 1432-2242
    Keywords: Key words Aegilops triuncialis ; Triticum aestivum ; Heterodera avenae ; Cereal cyst nematode ; Resistance gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The cereal cyst nematode (Heterodera avenae) is an important root parasite of common wheat. A high level of resistance was transferred to wheat from Aegilops triuncialis (TR lines) using the cross [(T. turgidum×Ae. triuncialis)×T. aestivum]. Low fertility (3–5 viable kernels per plant) was observed during the process but the surviving hybrid plants were highly vigorous. To obtain stable resistant lines further crosses to T. aestivum were performed. The resistance in TR lines seems to be transferred from the C genome of Ae. triuncialis (genomes CCUU). Ae. triuncialis was highly resistant to the two Spanish populations of H. avenae tested, as well as to four French races and two Swedish populations. The histological analysis showed a hypersensitive reaction in the roots of a resistant TR line inoculated with the Ha71 pathotype of H. avenae, whereas well-formed syncytia were observed in the roots of the susceptible control. Resistance to the H. avenae Ha71 pathotype seemed to be inherited as determined by a single dominant factor in the crosses between resistant TR lines and susceptible cultivars.
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    Behavioral ecology and sociobiology 42 (1998), S. 163-169 
    ISSN: 1432-0762
    Keywords: Key words Lek behavior ; Mating ecology ; Ideal free distribution ; Body size ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Male costs and benefits associated with male display size in field populations of an Australian lekking Drosophila species were examined. Results suggested that male mating success increased with display size, since matings appeared to be more common in large displays, and since the probability of males encountering a female increased as displays contained more males. Female encounter probabilities did not increase once about 20 males or more were present on a display. Male size and fighting costs tended to increase with display size. The distribution of males among displays did not follow the ideal free distribution in the sense that each male did not have equal mating opportunity per unit time. Deviation from an ideal free distribution may have been due to female preference for mating in aggregations rather than with solitary males, since in a field experiment females were more willing for mating in an aggregation of five males than with solitary males.
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  • 88
    ISSN: 1573-9368
    Keywords: particle bombardment ; transgene expression ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A population of R0 transgenic wheat plants, generated by particle bombardment, was analyzed to define molecular, genetic and phenotypic properties resulting from transformation with a cointegrate vector, or cotransformation with two separate plasmids. By evaluating the progeny of 70 independently-derived transgenic plants, we also identified rare events such as chimerism and transgene elimination, which provide valuable information concerning the development of transgenic cereal plants following bombardment experiments. The frequency of chimerism in our transgenic wheat plants was very low. Furthermore, while transgene elimination did occur, this was also a very rare event. We determined the copy numbers of integrated transgenes and the levels of transgene expression. Comparisons to transgenic rice plants generated in the same manner demonstrated some similarities, but also important differences in transgene behavior. Whereas in rice there is no evidence for any direct relationship between transgene copy number and transgene expression or stability, multicopy populations in wheat demonstrated a bias towards higher levels of expression for the two genes and the maize ubiquitin promoter evaluated in the present study.
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  • 89
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    Molecular genetics and genomics 258 (1998), S. 571-579 
    ISSN: 1617-4623
    Keywords: Key words Tetracycline repressor ; Inducible promoter ; Drosophila ; Aging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The “reverse” tetracycline repressor (rtR) binds a specific DNA element, the tetracycline operator (tetO), only in the presence of tetracycline, or derivatives such as doxycycline (dox). Fusion of rtR to the transcriptional activation domain of herpes virus protein VP16 produces a eukaryotic transactivator protein (rtTA). rtTA has previously been shown to allow dox-dependent transcription of transgenes linked to tetO sequences in mammals. To adapt this system to Drosophila, the Actin5C promoter was used to drive constitutive expression of rtTA in transgenic flies. Three reporter constructs, each encoding E. coli β-galactosidase (β-gal), were also introduced into transgenic flies. In one reporter seven tetO sequences were fused to the Adh core promoter. The other two reporter constructs contain seven tetO sequences fused to the hsp70 core promoter. Feeding of transgenic Drosophila containing the rtTA construct and any one of the three reporter constructs with dox caused up to 100-fold induction of β-gal. Dox induced β-gal expression in all tissues, in larvae and in young and senescent adults. Induction of β-gal in adults had no detectable effect on life span. These results suggest the potential usefulness of this system for testing specific genes for effects on Drosophila development and aging.
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  • 90
    ISSN: 1573-5028
    Keywords: calcium ; in situ hybridization ; multigene family ; polyploid ; signal transduction ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recently, we reported on the characterization of the calmodulin (CaM) gene family in wheat [44]. We classified wheat CaM genes into four subfamilies (SFs) designated SF-1 to SF-4, each representing a series of homoeoallelic loci on the homoeologous chromosomes of the three genomes of common wheat. Here we studied the expression of these wheat CaM genes in the course of wheat development. Northern blot analysis using SF-specific probes revealed differences in SF expression levels in different organs and stages of development. Subsequently, cell-specific expression of CaM SFs was investigated by in situ RNA hybridization. In developing seeds, all CaM SFs showed highest expression in the embryo and less in the aleurone and in the starchy endosperm. In primary roots, all four CaM SFs were expressed in the root cap, meristematic regions and in differentiating cells. During development of the roots, expression gradually decreased. The wheat glutenin gene, which was used as a control throughout our experiments, was found to be expressed in the starchy endosperm but not in the aleurone, embryos or vegetative tissues. In stems, at advanced stages of growth, differences in cell-specific expression of CaM SFs were found. For example, SF-2 was highly expressed in differentiating phloem fibers. Thus, CaM genes in common wheat exhibit a developmentally regulated organ-, tissue-, cell- and SF-specific expression patterns.
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  • 91
    ISSN: 1617-4623
    Keywords: Key words Cytochrome P450 ; Toxin resistance ; Multigene family ; Induction ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In vertebrates, cytochrome P450s of the CYP2 and CYP3 families play a dominant role in drug metabolism, while in insects members of the CYP6 and CYP28 families have been implicated in metabolism of insecticides and toxic natural plant compounds. A degenerate 3′ RACE strategy resulted in the identification of fifteen novel P450s from an alkaloid-resistant species of Drosophila. The strong (17.4-fold) and highly specific induction of a single gene (CYP4D10) by the toxic isoquinoline alkaloids of a commonly utilized host-plant (saguaro cactus) provides the first indication that members of the CYP4 family in insects may play an important role in the maintenance of specific insect-host plant relationships. Strong barbiturate inducibility of CYP4D10 and two other D. mettleri P450 sequences of the CYP4 family was also observed, suggesting a pattern of xenobiotic responsiveness more similar to those of several vertebrate drug-metabolizing enzymes than to putative vertebrate CYP4 homologs.
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  • 92
    ISSN: 1615-6102
    Keywords: Cucumis sativus ; Ethylene ; Ferric-reducing capacity ; Iron deficiency ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Dicotyledonous plants respond to Fe deficiency by enhancing the capacity of their roots to reduce Fe(III) to Fe(II). It has been suggested that there are two different ferric redox systems in the roots: the standard reductase, active with ferricyanide and not inducible by Fe deficiency, and the turbo reductase, active with both ferricyanide and ferric chelates and inducible by Fe deficiency. We have used different experimental approaches to test whether or not the Fe(III)-reducing capacity of cucumber (Cucumis sativus L. cv. Ashley) roots can be explained by considering the standard and the turbo reductase as the same enzyme. For this, we used both Fe-sufficient and Fe-deficient plants, which were treated with ethylene inhibitors (cobalt or silver thiosulfate; found to inhibit the turbo reductase in a previous work), a protein synthesis inhibitor (cycloheximide), or an mRNA polyadenylation inhibitor (cordycepin). At different times after application of these inhibitors, reduction of both ferricyanide and Fe(III)-EDTA were determined. In addition, we studied the effects of pH and temperature on the reduction of ferricyanide and Fe(III)-EDTA by both Fe-sufficient and Fe-deficient plants. Results suggest that there are, at least, two different ferric redox systems in the roots. Enhancement of Fe(III)-reducing capacity (turbo reductase) by Fe-deficient plants probably requires the de novo synthesis of a (or several) protein(s), which has a high turnover rate and whose expression is presumably regulated by ethylene.
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  • 93
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    Euphytica 100 (1998), S. 189-196 
    ISSN: 1573-5060
    Keywords: cytoplasmic effects ; inheritance ; quality ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The inheritances of thousand kernel weight (TKW), protein percentage, protein quality and grain hardness were studied through an 11 x 11 complete diallel set of bread wheat genotypes consisting of four alloplasmic lines of Selkirk, two alloplasmic lines of Siete Cerros 66, and five commercial cultivars. Genetic components accounted for 93%, 90%, 78%, and 92% of total variation for TKW, protein percentage, protein quality, and grain hardness, respectively. General combining ability (GCA) effects were dominant for TKW (48% GCA, 38% SCA [specific combining ability], and 7% reciprocal effects [RE]), protein percentage (70% GCA, 10% SCA, and 10% RE), and grain hardness (59% GCA, 29% SCA, and 4% RE). However, SCA effects dominated for protein quality (30% GCA, 43% SCA, and 5% RE). Broad- and narrow-sense heritabilities were estimated at 0.95 and 0.65 for TKW, 0.94 and 0.82 for protein percentage, 0.83 and 0.47 for protein quality, and 0.95 and 0.74 for grain hardness. Reciprocal effects were highly significant for all quality traits, but less effective than additive and non-additive gene effects. Aegilops cylindrica, Ae. ventricosa, and Triticum turgidum cytoplasms showed positive effects on TKW in some crosses. Ae. cylindrica, Ae. variabilis, and Ae. uniaristata cytoplasms seemed to have potential for improving protein percentage. T. aestivum cytoplasms were superior to alien cytoplasms for protein quality. Bolal 2973, Kiraç 66 and Bezostaja 1 cytoplasms increased protein quality in some crosses. Ae. cylindrica, Ae. variabilis, Ae. ventricosa and Ae. uniaristata cytoplasms had significant effects on grain hardness. The cytoplasmic variation in B type T. aestivum cytoplasm was found to be significant for all traits.
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  • 94
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; combining ability ; heterosis ; genetic distance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In wheat, the possibility of introducing F1 seed into practical agriculture has been greatly enhanced by the discovery of effective chemical hybridising agents (CHAs). Although some technical and economic problems concerning the use of CHAs for large-scale production of F1 seed remain to be solved, a first group of F1 hybrids has been submitted for registration in several European countries i.e., France, England and Italy. Combining ability for grain yield and several agronomic and quality traits was studied in an eight-parent diallel cross. Highly significant combining ability effects were observed for all the traits while specific combining ability effects were statistically significant for grain yield, plant height, heading time and Chopin alveograph parameter P. The level of genetic diversity between parents as estimated using molecular markers is considered a tool for predicting the hybrid performance and heterosis of crosses. To explore this possibility, RFLP and RAPD markers were used to predict the performance of hybrids obtained from diallel and top crosses. The performance of the hybrids was determined in replicated plot trials sown at normal seed density in several locations. Coefficient of parentage (rp), based on pedigree information for all the pairwise combinations of the parents ranged from 0.01 to 0.34. The parents were assayed for random amplified polymorphic DNA (RAPD) with 87 primers which generated 304 polymorphic bands. Genetic similarity between parents, estimated on the basis of common bands using the Jaccard's similarity coefficient (J), ranged from 0.25 to 0.57. Correlation between parental diversity and hybrid performance was generally weak. A positive trend is observed in the yield potential of the hybrids produced in Italy in the last 10 years. In fact among the first set of hybrids produced by random crossing of the available cultivars, none produced 10% more than the checks whereas the last generation of hybrids includes combinations yielding 15% more than the best standards. Our results clearly indicate the need to develop specific strategies in order to identify and/or to select parental lines with a high level of general combining ability (GCA) and specific combining ability (SCA). The information regarding the genetic diversity of the parental lines do not appear helpful for predicting F1 performance.
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  • 95
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    Euphytica 101 (1998), S. 9-16 
    ISSN: 1573-5060
    Keywords: heading time ; Triticum aestivum ; vernalisation response ; Vrn – genotypes ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Substitution lines with reciprocal substitutions of chromosomes containing recessive alleles of the homoeologous group 5 chromosomeVrn genes between varieties of winter wheat with high vernalisation requirement (‘Mironovskaya 808’) and low vernalisation requirements (‘Bezostaya 1’) have been created. On this basis the genetic determination of vernalisation requirement was established. Substitution lines Mironovskaya 808 (Bezostaya 1 5A), Mironovskaya 808 (Bezostaya 1 5B), Mironovskaya 808 (Bezostaya 1 5D) and reciprocal substitution lines Bezostaya 1 (Mironovskaya 808 5A), Bezostaya 1 (Mironovskaya 808 5B) and Bezostaya 1 (Mironovskaya 808 5D) were grown under different durations of vernalisation (3, 4, 5, 6, 7 and 8 weeks) and their response was evaluated. Photoperiodic sensitivity of the original parental genotypes was also determined. Reciprocal substitution lines of the same chromosome that carries the same vrn allele responded differently to vernalisation deficit. Differences have been shown between all group 5 reciprocal substitutions. Lines carrying chromosomes 5A and 5D of Mironovskaya 808 had a high vernalisation requirement whereas lines carrying chromosome 5B of Bezostaya 1 (vrn2B) had a low vernalisation requirement. The reciprocal lines had a reverse requirement. This explains the different vernalisation requirements of the original varieties: Mironovskaya 808 with a high vernalisation requirement carries two alleles (vrn1M and vrn3M) in its genotype that increase the vernalisation requirement, whereas Bezostaya 1 with a lower requirement for vernalisation contains only one such allele (vrn2B). By combination of the alleles in the lines with the substitution of chromosome 5B carrying vrn2 allele that in both original genotypes work inversely to the other alleles, transgressive genotypes have been formed: genotype vrn1M vrn2B vrn3M determines a higher vernalisation requirement than original variety Mironovskaya 808, and genotype vrn1B vrn2M vrn3B determines a lower vernalisation requirement than the original Bezostaya 1. An incomplete vernalisation requirement prolonged the time to heading, with exponential dependence on the vernalisation deficit, or prevented heading altogether. The original varieties further differed in photoperiodic sensitivity (Mironovskaya 808 sensitive, Bezostaya 1 less sensitive) that also influenced the background of substitution lines. The impact of the background on the heading time showed itself by about one week difference between Mironovskaya 808 and Bezostaya 1 grown under 8 weeks vernalisation and normal photoperiod. The difference between the lines with Mironovskaya 808 background and the lines with Bezostaya 1 background was approximately the same and was not significantly changed in different vernalisation variants of the lines. This difference may be caused by different photoperiodic sensitivity of the original varieties, but also by other genes, such as genes of earliness per se.
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  • 96
    ISSN: 1573-5060
    Keywords: bread wheat ; Triticum aestivum ; tolerance to deoxynivalenol ; somaclonal variant ; in vitro selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study was conducted to develop an efficient in vitro selection system for scab resistance by using in vitro screening for tolerance to deoxynivalenol (DON). Immature embryos of two wheat varieties, a scab-resistant variety Sumai 3 and a susceptible variety Mianyang 11, and their reciprocal F1 hybrids were cultured on MS medium supplemented with 2,4-D 2 mg/l and 0.6 × 10-4 M DON for callus induction. The responses of callus induction and plant regeneration to 0.6 × 10-4 M DON differed significantly between resistant and susceptible varieties, according to observed scab resistance levels at the plant level in the field. The percentage of callus formation of resistant variety Sumai 3 on induction medium containing DON was higher than that of susceptible variety Mianyang 11. Regeneration of DON-tolerant calli on DON-containing differentiation medium differed significantly between Sumai 3 and Mianyang 11. Averaged across the DON-tolerant calli of two varieties and their reciprocals, regeneration of DON-tolerant calli was decreased 3-fold on DON-containing medium. By an inoculation test with conidiospores of Fusarium graminearum Schw, we obtained several resistant lines from progenies of regenerated plants from DON-tolerant calli. These somaclonal lines had lower disease scoring (reaction index, infected spikelets and disease incidence), shorter plants and better yield components than Sumai 3, a famous Chinese resistant variety.
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  • 97
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; Secale cereale ; T1BL.1RS ; chromosome substitution and translocation ; yield components
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The T1BL.1RS wheat (Triticum aestivum L.) - rye (Secale cereale L.) translocations have been of particular interest and are widely used in bread wheat breeding programs. The objective of this study was to determine the effect of the T1BL.1RS chromosome on grain yield and its components using 20 near-isolines of spring bread wheat cultivar ‘Seri M82’ (10 homozygous for chromosome 1B substitution and 10 homozygous for T1BL.1RS). The test lines have been produced by substituting the 1B chromosome in Seri M82 (T1BL.1RS, T1BL.1RS) through backrossing. Two field experiments were evaluated under optimum (five irrigations) and reduced (one irrigation) moisture conditions for two consecutive production cycles at the Mexican National Agricultural Research Institute, Ciudad Obregon, Sonora, Mexico. The presence of T1BL.1RS had a significant effect on grain yield, harvest index, grains/m2, grains/spike, 1000-grain weight, test weight, flowering date and physiological maturity in both moisture conditions. The agronomic advantage of the 1B substitution lines on above-ground biomass yield at maturity, spikes/m2and grain-filling duration was expressed only under the optimum moisture condition. The presence of T1BL.1RS increased grain yield 1.6% and 11.3% for optimum and reduced moisture conditions, respectively. These results encourage further use of T1BL.1RS wheats in improving agronomic traits, especially for reduced irrigation or rainfed environments.
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  • 98
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    Euphytica 104 (1998), S. 39-47 
    ISSN: 1573-5060
    Keywords: drought resistance ; diallel graph ; gene action ; excised-leaf water loss ; relative water content ; bread wheat ; osmotic adjustment ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Little information is available on the genetics of excised leaf water loss and relative water content in wheat. An experiment conducted on the F1 generation from a half-diallel set of crosses involving two drought tolerant, two moderately tolerant and two sensitive varieties was initiated to investigate the inheritance of excised-leaf water loss and relative water content. This experiment was conducted under glass-house and field conditions at tillering and anthesis stages of plant development. Additive gene action, in general, played a major role in determining the inheritance of these traits. General combining ability (GCA) was the main source of genetic variation among crosses, while specific combining ability (SCA) was negligible. Strong phenotypic correlations existed between per se performance and GCA effects in the majority of cases. Heterosis was unimportant. Genotype-environmental interactions and/or differential gene expression appeared to account for different results found between environments and growth stages, respectively. Selection for relative water content appeared to be more effective at anthesis, while for excised-leaf water loss at both stages of plant growth. In addition to drought resistance, wide differences for morphological characters and relative positions of parental arrays revealed the possibility of obtaining desirable segregants for drought stress conditions from the cross Kharchia 65 × WH 147.
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  • 99
    ISSN: 1573-5036
    Keywords: biomarker ; cadmium ; copper ; heavy metal ; PC ; PC-SH ; phytochelatin ; stress ; toxicity ; Triticum aestivum ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Heavy metal contaminated soils often show increased levels of more than one metal, e.g. copper (Cu), cadmium (Cd), zinc (Zn), lead (Pb) or nickel (Ni). In case such soils are used for crop production, prediction of yield reduction or quality decline due to heavy metals in the soil is inadequate when based only on chemical soil analysis. The use of biomarkers such as phytochelatins (PC), non-protein thiols specifically induced in plants upon exposure to heavy metals, may be an additional tool or diagnostic criterion in heavy metal research and in practice. In the present work, Cu and Cd uptake and induction of PC synthesis are studied with hydroponically grown maize and wheat plants exposed to mixtures of the two metals. We observed a close positive relationship between the concentrations of Cd and PC in the plant shoot material. A decreased shoot concentration of Cd after addition of Cu, due to metal competition at common root absorption sites, coincided with lower shoot PC levels. Also differences in metal uptake and xylary metal transport among the two plant species were reflected in corresponding differences in PC concentration. The observed direct relationship between shoot PC concentration and the degree of metal-induced growth inhibition makes the use of PC promising for the purpose tested for.
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  • 100
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; Puccinia recondita ; leaf rust ; breeding ; resistance ; yield ; yield components
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The most important breeding objectives in crop improvement are improving grain yield, grain quality, and resistances to various biotic and abiotic stresses. The objectives of our study were to compare two crossing and four selection schemes for grain yield, yield traits, and slow rusting resistance to leaf rust (Puccinia recondita) based on additive genes in wheat (Triticum aestivum), and to identify the most efficient crossing and selection methodologies in terms of genetic gains and cost efficiency. Segregating populations were derived from 18 simple crosses and the same number of top (three-way) crosses. Half of the crosses were derived from Yecora 70 and the other half from Veery #10 as the common leaf rust susceptible parents. The four selection schemes were: pedigree, modified bulk (F2 and F1-top as pedigree, selected lines in F3, F4, F2-top, F3-top as bulk; and pedigree in F5 and F4-top populations), selected bulk (selected plants in F2, F3, F4, F1-top, F2-top and F3-top as bulk; and pedigree in F5 and F4-top populations), and nonselected bulk (bulk in F2, F3, F4, F1-top, F2-top and F3-top; and pedigree in F5 and F4-top populations). A total of 320 progeny lines, parents and checks were tested for grain yield, other agronomic traits and leaf rust resistance during the 1992/93 and 1993/94 seasons in Ciudad Obregon (Sonora State, Mexico) which represents a typical high yielding irrigated site. The influence of the type of cross and the selection scheme on the mean grain yield and other traits of the progenies was minimal. The selection of parents was the most important feature in imparting yield potential and other favourable agronomic traits. Moreover, the highest yielding lines were distributed equally. Progeny lines derived from Veery #10 crosses had significantly higher mean grain yield compared to those derived from the Yecora 70 crosses. Furthermore, a large proportion of the highest yielding lines also originated from Veery #10 crosses. Mean leaf rust severity of the top cross progenies was lower than that of the simple cross progenies possibly because two parents contributed resistance to top cross progenies. Mean leaf rust severity of the nonselected bulk derivatives was twice that of lines derived from the other three schemes. Selected bulk appears to be the most attractive selection scheme in terms of genetic gains and cost efficiency.
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