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  • Articles  (450)
  • Triticum aestivum  (229)
  • photosynthesis  (224)
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  • 1995-1999  (450)
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  • Springer  (450)
  • American Chemical Society
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  • 1
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    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
    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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  • 3
    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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  • 4
    ISSN: 1432-0789
    Keywords: 15N-labelled fertilizer ; Added N interaction Fertilizer N uptake ; Soil N uptake ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of 15N-labelled ammonium nitrate, urea and ammonium sulphate on yield and uptake of labelled and unlabelled N by wheat (Triticum aestivum L. cv. Mexi-Pak-65) were studied in a field experiment. The dry matter and N yields were significantly increased with fertilizer N application compared to those from unfertilized soil. The wheat crop used 64.0–74.8%, 61.5–64.7% and 61.7–63.4% of the N from ammonium nitrate, urea and ammonium sulphate, respectively. The fertilizer N uptake showed that ammonium nitrate was a more available source of N for wheat than urea and ammonium sulphate. The effective use of fertilizer N (ratio of fertilizer N in grain to fertilizer N in whole plant) was statistically similar for the three N fertilizers. The application of fertilizer N increased the uptake of unlabelled soil N by wheat, a result attributed to a positive added N interaction, which varied with the method of application of fertilizer N. Ammonium nitrate, urea and ammonium sulphate gave 59.3%, 42.8% and 26.3% more added N interaction, respectively, when applied by the broadcast/worked-in method than with band placement. A highly significant correlation between soil N and grain yield, dry matter and added N interaction showed that soil N was more important than fertilizer N in wheat production. A values were not significantly correlated with added N interaction (r=0.719). The observed added N interaction may have been the result of pool substitution, whereby added labelled fertilizer N stood proxy for unlabelled soil N.
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  • 5
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    Biology and fertility of soils 23 (1996), S. 327-331 
    ISSN: 1432-0789
    Keywords: CO2 emission ; Field method ; Soil respiration ; Triticum aestivum ; Soil moisture ; Carbon reservoirs ; Greenhouse effect ; Grey forest soil ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The dynamics of the rate of CO2 evolution from soil in fallow and croplant under spring wheat (Triticum aestivum L.) was studied in a crop rotation in grey forest soil of the Baikal forest-steppe during the growing season and in different years. It was shown that the regional characteristics of soils and hydrothermal conditions in different years affect the rate of CO2 evolution in agroecosystems. The seasonal dynamics of CO2 is characterized by insignificant changes in the autumn to spring period and enhanced emission in hot and dry summers. CO2 evolution is assumed to increase due to enhanced mineralization and partial diffusion from the carbonate horizon at the depth of the seasonal frost. During the growing season the dynamics of CO2 evolution depends on the soil moisture regime. There was a strong correlation between the rate of CO2 emission and soil moisture in the particularly dry year of 1993 (η=0.86) and a moderate correlation in the other years (η=0.38–0.54). The effect of the previous crop and fertilizer application on the rate of CO2 emission was insignificant. In a continuous fallow the total carbon release into the atmosphere varied throughout the years studied from 558 to 1880 kg ha-1. Humus losses varied from 0.9% to 3.1%.
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  • 6
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    Biology and fertility of soils 23 (1996), S. 327-331 
    ISSN: 1432-0789
    Keywords: Key words CO2 emission ; Field method ; Soil respiration ; Triticum aestivum ; Soil moisture ; Carbon reservoirs ; Greenhouse effect ; Grey forest soil ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The dynamics of the rate of CO2 evolution from soil in fallow and cropland under spring wheat (Triticum aestivum L.) was studied in a crop rotation in grey forest soil of the Baikal forest-steppe during the growing season and in different years. It was shown that the regional characteristics of soils and hydrothermal conditions in different years affect the rate of CO2 evolution in agroecosystems. The seasonal dynamics of CO2 is characterized by insignificant changes in the autumn to spring period and enhanced emission in hot and dry summers. CO2 evolution is assumed to increase due to enhanced mineralization and partial diffusion from the carbonate horizon at the depth of the seasonal frost. During the growing season the dynamics of CO2 evolution depends on the soil moisture regime. There was a strong correlation between the rate of CO2 emission and soil moisture in the particularly dry year of 1993 (η=0.86) and a moderate correlation in the other years (η=0.38–0.54). The effect of the previous crop and fertilizer application on the rate of CO2 emission was insignificant. In a continuous fallow the total carbon release into the atmosphere varied throughout the years studied from 558 to 1880 kg ha–1. Humus losses varied from 0.9% to 3.1%.
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  • 7
    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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  • 8
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    Biology and fertility of soils 23 (1996), S. 273-281 
    ISSN: 1432-0789
    Keywords: Wheat ; Triticum aestivum ; Rhizosphere ; Soil microflora ; Gram-negative bacteria ; API 20 NE ; Flavobacterium spp ; Cytophaga
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We identified 161 Gram-negative bacterial strains isolated from the root surface of wheat grown under different soil conditions. The strains were divided into seven groups based on major morphological and physiological properties. Taxonomic allocation of the groups was verified by guanine+cytosine contents of DNA. Except for one group, which may be assumed to include bacteria belonging to the genera Flavobacterium and Cytophaga, the various groups were taxonomically united. The distribution of the groups changed with soil improvement. Pseudomonads predominated in unimproved soil, but Flavobacterium and Cytophaga spp. were predominant in the most improved soil. As all the strains were non-fermentative by Hugh and Leifson's test, API 20NE identification was applied. However, many strains were misidentified by this system, especially in the Flavobacterium and Cytophaga spp. group. For ecological studies, the strains were classified to species level by the API 20 NE system and by the results of a combination of guanine+cytosine (mol%) and isoprenoid quinone data. The pattern of distribution of the bacteria on the root surface of wheat varied at species level within one genus depending on soil conditions.
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  • 9
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    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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  • 10
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    Nutrient cycling in agroecosystems 44 (1995), S. 205-215 
    ISSN: 1573-0867
    Keywords: Incubation of phosphorus in soil ; relative effectiveness ; superphosphate ; ×Triticosecale ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Single superphosphate was incubated for six months at 25°C in soil which had been subject to one of three moisture treatments. These were: dried in a glasshouse, dried at a constant temperature of 25°C, or moist soil. Phosphorus (P) effectiveness was then compared with effectiveness of P from freshly-applied superphosphate using yields of wheat (Triticum aestivum) and triticale (×Triticosecale) tops in pot experiments. Incubation in soil which had been dried at 25°C did not decrease the effectiveness of the P. Incubation in moist soil decreased it to about 20% of the effectiveness of freshly-applied P in one case and to about 50% in the other case. Incubation in soil which had been dried in a glasshouse also decreased its effectiveness. The decrease varied with conditions, but in two cases the P was 70% as effective as freshly-applied P, and in one case only 45% as effective. Presumably sufficient moisture was present in the soil dried in the glasshouse to enable water-soluble P present in the fertilizer to react with the soil.
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  • 11
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    Mangroves and salt marshes 2 (1998), S. 99-107 
    ISSN: 1572-977X
    Keywords: conductance ; mangrove ; photosynthesis ; productivity ; water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Diurnal gas exchange characteristics were measured simultaneously in two mangrove species, Avicennia marina and Bruguiera gymnorrhiza, over 7 d in summer (February–March), to compare their productivity. The study was undertaken in the Beachwood Mangroves Nature Reserve, Durban, South Africa, using fully expanded leaves of young and mature trees at the top of the canopy. Gas exchange was strongly influenced by photosynthetic photon flux density (PPFD), leaf temperature and the accompanying leaf to air vapour pressure deficit (Δ w). Carbon dioxide exchange was saturated at a PPFD of about 600 μmol m-2s-1 in B. gymnorrhiza compared to 800 μmol m-2s-1 in A. marina. Maximal CO2 exchange occurred between 12h00 and 14h00 and was consistently greater in A. marina (8.8 μmol m-2s-1) than in B. gymnorrhiza (5.3 mu;mol m-2s-1). Mean internal CO2 concentrations ( ci) were 260 μl l-1 in A. marina and 252 μl l-1 in B. gymnorrhiza. Photorespiratory activity was 32% in A. marina and 30% in B. gymnorrhiza. Mean water use efficiency (WUE) was 8.0 μmol mmol-1 in A. marina and 10.6 μmol mmol-1 in B. gymnorrhiza. Diurnal leaf water potentials ranged from –0.8 to –3.5 MPa and were generally lower in A. marina.
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  • 12
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    Mangroves and salt marshes 2 (1998), S. 191-198 
    ISSN: 1572-977X
    Keywords: canopy ; Hinchinbrook ; leaf area index ; mangrove ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Data on stand structure and rates of photosynthesis were used to estimate net canopy carbon fixation and carbon accumulation as living biomass in mangrove forests in Hinchinbrook Channel, Australia. Total annual canopy net carbon fixation was estimated to be about 29 t C ha−1 yr−1. This equates to about 204,000 t C yr−1 for all mangrove forests in Hinchinbrook Channel. Of this, only about 12% was stored as living plant biomass. Although it is not yet possible to present a robust carbon balance for mangrove trees, the remainder is presumably lost through plant respiration, litter fall, root turnover and exudation of organic compounds from roots.
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  • 13
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    Mangroves and salt marshes 3 (1999), S. 147-153 
    ISSN: 1572-977X
    Keywords: conductance ; gas exchange ; mangrove ; photorespiration ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic characteristics were investigated in the geographically isolated and restricted mangrove species, P.rhizophoreae. Gas exchange measurements were made on two to seven years old hydroponically grown plants maintained in 10%, 50% and 100% seawater. CO2 exchange in the 50% and 100% seawater treatments was reduced by 10% and 26%, respectively, compared to the 10% seawater treatment. CO2 response curves indicated that carboxylation efficiency was greater in 10% than in 50% seawater, while stomatal limitation increased from 11% to 16% as salinity increased from 10% to 50% seawater. Carbon losses via photorespiration (31% and 41%) and CO2 compensation point (67 and 81 μ11−1) were greater in 50% than in the 10% seawater treatment. Maximal CO2 exchange occurred at 30 °C with no differences among the salinity treatments. The results indicate that P. rhizophoreae exhibits many gas exchange characteristics previously reported for other mangroves.
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  • 14
    ISSN: 1432-1939
    Keywords: Key words Agrostis canina ; CO2 vents ; photosynthesis ; lignification ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The aim of this study was to characterise growth and photosynthetic capacity in plants adapted to long-term contrasting atmospheric CO2 concentrations (C a). Seeds of Agrostis canina L. ssp. monteluccii were collected from a natural CO2 transect in central-western Italy and plants grown in controlled environment chambers at both ambient and elevated CO2 (350 and 700 μmol mol−1) in nutrient-rich soil. Seasonal mean C a at the source of the plant material ranged from 610 to 451 μmol CO2 mol−1, derived from C4 leaf stable carbon isotope discrimination (δ13C). Under chamber conditions, CO2 enrichment stimulated the growth of all populations. However, plants originating from elevated C a exhibited higher initial relative growth rates (RGRs) irrespective of chamber CO2 concentrations and a positive relationship was found between RGR and C a at the seed source. Seed weight was positively correlated with C a, but differences in seed weight were found to explain no more than 34% of the variation in RGRs at elevated CO2. Longer-term experiments (over 98 days) on two populations originating from the extremes of the transect (451 and 610 μmol CO2 mol−1) indicated that differences in growth between populations were maintained when plants were grown at both 350 and 700 μmol CO2 mol−1. Analysis of leaf material revealed an increase in the cell wall fraction (CWF) in plants grown at elevated CO2, with plants originating from high C a exhibiting constitutively lower levels but a variable response in terms of the degree of lignification. In vivo gas exchange measurements revealed no significant differences in light and CO2 saturated rates of photosynthesis and carboxylation efficiency between populations or with CO2 treatment. Moreover, SDS-PAGE/ LISA quantification of leaf ribulose bisphosphate carboxylase/oxygenase (Rubisco) showed no difference in Rubisco content between populations or CO2 treatments. These findings suggest that long-term adaptation to growth at elevated CO2 may be associated with a potential for increased growth, but this does not appear to be linked with differences in the intrinsic capacity for photosynthesis.
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  • 15
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    Sexual plant reproduction 8 (1995), S. 266-272 
    ISSN: 1432-2145
    Keywords: Triticum aestivum ; Alloplasmic lines ; Apomixis ; Parthenogenesis ; Protein patterns ; 2-D gel electrophoresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An in vivo model system to study the initiation of embryo development is presented. From the so-called Salmon system of wheat (alloplasmic lines with a 1BL-1RS chromosome translocation), three completely isogenic and homozygous lines were produced by selection for uniformity in about 20 selfing/backcross generations as well as between sublines of doubled haploids. The line (aestivum)-Salmon is male fertile and sexual. The lines (caudata)-Salmon and (kotschyi)-Salmon are male sterile and have a parthenogenetic capacity of about 90%. The expression of nuclear-cytoplasmic male sterility is different for the two parthenogenetic lines. The initiation of autonomous embryo development at defined developmental stages of the ovaries and the maximum degree of parthenogenesis are identical in both parthenogenetic lines as proved by the auxin test and progeny analyses. The protein patterns from ovary extracts of the three isogenic lines were identical for more than 200 spots of 2-D polyacrylamide gels, confirming their homogeneity. However, one protein (P 115.1) was found 3 days before and during anthesis only in ovaries of the parthenogenetic lines. It seems to be involved in the initiation of parthenogenesis.
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  • 16
    ISSN: 1432-2145
    Keywords: Key words Male sterility ; Starch ; Triticum aestivum ; Water stress ; Anther ; Pollen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Water deficit during meiosis in microspore mother cells of wheat (Triticum aestivum L.) induces male sterility, which reduces grain yield. In plants stressed during meiosis and then re-watered, division of microspore mother cells seems to proceed normally, but subsequent pollen development is arrested. Stress-affected anthers generally lack starch. We employed light microscopy in conjunction with histochemistry to compare the developmental anatomy of water-stress-affected and normal anthers. The earliest effects of stress, detectable between meiosis and young microspore stages, were the degeneration of meiocytes, loss of orientation of the reproductive cells, and abnormal vacuolization of tapetal cells. Other effects observed during subsequent developmental stages were deposition of starch in the connective tissue where it is normally not present, hypertrophy of the middle layer or endothecial cells, and deposition of sporopollenin-like substances in the anther loculus. The resulting pollen grains lacked both starch and intine. These results suggest that abnormal degeneration of the tapetum in water-stressed anthers coupled with a loss of orientation of the reproductive cells could be part of early events leading to abortion of microspores.
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  • 17
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    Plant cell reports 16 (1997), S. 663-667 
    ISSN: 1432-203X
    Keywords: Key words Embryogenesis ; Ovule culture ; Triticum aestivum ; Zygote
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ovules of the wheat breeding line Veery #5 were excised and transferred to culture within 24 h after pollination. When ovules were cultured on Phytagel-solidified medium, and the pericarp removed exclusively at the micropylar tip and the abaxial side, zygotes from up to 79.2% of the ovules underwent embryogenesis with the same developmental pattern as found in planta. Embryos from more than 50% of the cultured ovules germinated when transferred to regeneration medium. More than 100 plantlets were randomly chosen for transfer to soil, all of which developed to phenotypically normal and fertile plants. With this system, the entire process of zygotic embryogenesis can be studied using living material. Furthermore, the method could be used as an embryo rescue technique for plant breeding purposes.
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  • 18
    ISSN: 1432-203X
    Keywords: Key words Abscisic acid ; Anther culture ; Light ; Metallothionein ; Pollen embryogenesis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cloned cDNA to the wheat (Triticum aestivum) early cysteine-labeled metallothionein has many characteristics of a molecular marker for pollen embryogenesis in this plant. This transcript was not detected in uninucleate microspores at the time of culture or in pollen at any stage during normal ontogeny; its mRNA did begin to increase in embryogenic microspores within 6 h of culture, peaked at around 24 h, declined, then leveled off through the 21-day-old embryoid stage. Additionally, the accumulation of the embryoid-abundant EcMt gene transcript showed a direct and positive correlation with an increase of ABA in embryogenic microspores and developing pollen embryoids. Irradiating cultures with high intensity white light or with far-red, or blue light, suppressed EcMt transcript accumulation and the ability of microspores to form embryoids; however, light did not affect ABA concentrations during the early stages of culture. These results suggest that although a promoter of pollen embryogenesis in bread wheat, ABA alone cannot maintain the sporophytic differentiation of microspores subjected to inhibitory regimes of light in vitro. Whether or not light acts directly or indirectly in suppressing EcMt gene expression and pollen embryogenesis remains unknown.
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  • 19
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    Water, air & soil pollution 85 (1995), S. 1461-1466 
    ISSN: 1573-2932
    Keywords: ozone ; wheat ; Triticum aestivum ; growth ; senescence ; biomass partitioning ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In closed-chamber fumigation experiments dry matter partitioning and chlorophyll fluorescence of wheat were studied, analysing the effects of ozone during different stages of plant development. Ozone causes enhanced leaf senescence, leading to a loss of green leaf area and, consequently to a decreased supply of assimilates, affecting (in increasing order of severeness) stem, ear and grain productivity because of reduced storage pools for translocation. Leaves of plants before shooting stage were most sensitive but the lack of green leaf area after ear emergence had the most pronounced effects on grain yield. Measurements of photochemical capacity showed that evidence for negative ozone effects could be found in changes of chlorophyll fluorescence parameters in leaf sections not yet showing visible ozone injury. Negative effects on photosynthesis were more distinct with increasing accumulated ozone dose, with increasing age of leaf tissue and with increasing ozone sensitivity of the cultivar. The changes in chlorophyll fluorescence are most likely to be explained by a decreased pool size of plastoquinones caused by ozone.
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  • 20
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    Plant molecular biology 27 (1995), S. 435-439 
    ISSN: 1573-5028
    Keywords: buoyant separation ; cloning ; extrachromosomal DNA ; germination ; telomere ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A procedure developed orginally for selective extraction of viral (extrachromosomal) DNA from virus-infected mammalian cells was applied to cell nuclei isolated from uninfected wheat embryos. The resulting nuclear extrachromosomal DNA (exDNA) was enriched for telomere-type sequences by isopycnic centrifugation and inserted into the Sma I site of pUC119. A cloned DNA fragment (241 bp) was found to consist primarily of tandemly repeated heptamere units of the same sequence (5′-CCCTAAA-3′) that is known to predominate in telomeric DNA of Arabidopsis thaliana. Hybridization experiments indicate that extrachromosomal telomeric repeats are abundant in resting embryos and disappear rapidly during germination.
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  • 21
    ISSN: 1573-5028
    Keywords: Cell cycle ; circadian clock ; green alga ; GTP-binding proteins ; light regulation ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract ADP-ribosylation factor (ARF) is a highly conserved, low molecular mass (ca. 21 kDa) GTP-binding protein that has been implicated in vesicle trafficking and signal transduction in yeast and mammalian cells. However, little is known of ARF in plant systems. A putative ARF polypeptide was identifed in subcellular fractions of the green alga Chlamydomonas reinhardtii, based on [32P]GTP binding and immunoblot assays. A cDNA clone was isolated from Chlamydomonas (Arf1), which encodes a 20.7 kDa protein with 90% identity to human ARF1. Northern blot analyses showed that levels of Arf1 mRNA are highly regulated during 12 h/12 h light/dark (LD) cycles. A biphasic pattern of expression was observed: a transient peak of Arf1 mRNA occurred at the onset of the light period, which was followed ca. 12 h later by a more prominent peak in the early to mid-dark period. When LD-synchronized cells were shifted to continuous darkness, the dark-specific peak of Arf1 mRNA persisted, indicative of a circadian rhythm. The increase in Arf1 mRNA at the beginning of the light period, however, was shown to be light-dependent, and, moreover, dependent on photosynthesis, since it was prevented by DCMU. We conclude that the biphasic pattern of Arf1 mRNA accumulation during LD cycles is due to regulation by two different factors, light (which requires photosynthesis) and the circadian clock. Thus, these studies identify a novel pattern of expression for a GTP-binding protein gene.
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  • 22
    ISSN: 1573-5028
    Keywords: gene expression ; photosynthesis ; protein turnover ; psbA ; tac promoter ; D1 protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Over-expression of the psbAIII gene encoding for the D1 protein (form II; D1:2) of the photosystem II reaction centre in the Synechococcus sp. PCC 7942 was studied using a tac promoter and the lacI Q system. Over-expression was induced with 40 μg/ml IPTG in the growth medium for either 6 or 12 h at growth irradiance (50 μmol photons m-2 s-1). This treatment doubled the amount of psbAII/III mRNA and the D1:2 protein in membranes but decreased the amount of psbAI messages and the D1:1 protein. The total amount of both heterodimeric reaction centre proteins, D1 and D2, remained constant under growth light conditions, indicating that the number of PSII centres in the membranes was not affected, only the form of the D1 protein was changed from D1:1 to D1:2 in most centres. When the cells were photoinhibited either at 500 or 1000 μmol photons m-2 s-1, in the presence or absence of the protein synthesis inhibitor lincomycin, the D1:2 protein remained at a higher level in cells in which over-expression had been induced by IPTG. These cells were also less prone to photoinhibition of PSII. It is suggested that the tolerance of cells to photoinhibition increases when most PSII reaction centres contain the D1:2 protein at the beginning of high irradiance. This tolerance is further strengthened by maintaining psbAIII gene over-expression during the photoinhibitory treatment.
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  • 23
    ISSN: 1573-5028
    Keywords: ACC synthase ; differential expression ; ethylene ; root-specific expression ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two partial 1-aminocyclopropane-1-carboxylic acid (ACC) synthase cDNA clones (pWAS1, 1089 bp; andpWAS3, 779 bp) were isolated by polymerase chain reaction (PCR) using cDNA to total mRNA purified from etiolated wheat seedlings as template and degenerate oligonucleotides synthesized based on the regions of the ACC synthase amino acid sequence that are highly conserved among different plants. Northern analysis showed that the expression of the corresponding genes are differentially regulated. While the transcripts ofpWAS1 were found in all the tissues of wheat that were tested with a maximum level at the early stages of spike development,pWAS3 mRNA was present almost exclusively in the root. A 5590-bp genomic clone,TA-ACS2, corresponding topWAS3 cDNA has been isolated. TheTA-ACS2 sequence consists of a 589-bp 5′-upstream region, 2743 bp of transcribed region with four exons and three introns and a 3′-downstream region of 2257 bp. Expression inEscherichia coli confirmed the ACC synthase activity of TA-ACS2 polypeptide. Sequence comparisons show that the two wheat ACC synthases are more similar to each other and to the rice ACC synthase,OS-ACS1, at the nucleotide level than at the amino acid level. The amino acid sequence of TA-ACS2 is most similar (66.1% identity) to that of broccoli. The chromosomal location of both wheat ACC synthase genes have been determined by aneuploid analysis.TA-ACS1 is located on the short arm of chromosomes 7A and 7D and on the long arm of chromosome 4A.TA-ACS2 is located on the long arm of homoeologous group 2 chromosomes.
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  • 24
    ISSN: 1573-5028
    Keywords: abscisic acid ; early cysteine-labeled protein ; fluridone ; metallothioneins ; pollen embryogenesis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A clone for an embryoid-abundant, early cysteine-labeled metallothionein (EcMt) gene has been isolated from a wheat pollen embryoid cDNA library. The transcript of this gene was only expressed in embryogenic microspores, pollen embryoids, and developing zygotic embryos of wheat. Accumulation of the EcMt mRNA showed a direct and positive correlation with an increase of the plant hormone, abscisic acid (ABA) in developing pollen embryoids. Treating cultures with an inhibitor of ABA biosynthesis, fluridone, suppressed not only ABA accumulation but also the appearance of the EcMt gene transcript and the ability of microspores to form embryoids. These results suggest that the EcMt gene may act as a molecular marker for pollen embryogenesis because ABA biosynthesis is accompanied by the increased expression of the EcMt transcript that coincides with the differentiation of pollen embryoids in wheat anther cultures.
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  • 25
    ISSN: 1573-5028
    Keywords: antisense ; Corynebacterium glutamicum ; Escherichia coli ; Flaveria trinervia ; overexpression ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phosphoenolpyruvate carboxylase (PEPC) genes from Corynebacterium glutamicum (cppc), Escherichia coli (eppc) or Flaveria trinervia (fppc) were transferred to Solanum tuberosum. Plant regenerants producing foreign PEPC were identified by Western blot analysis. Maximum PEPC activities measured in eppc and fppc plants grown in the greenhouse were doubled compared to control plants. For cppc a transgenic plant line could be selected which exhibited a fourfold increase in PEPC activity. In the presence of acetyl-CoA, a known activator of the procaryotic PEPC, a sixfold higher activity level was observed. In cppc plants grown in axenic culture PEPC activities were even higher. There was a 6-fold or 12-fold increase in the PEPC activities compared to the controls measured in the absence or presence of acetyl-CoA, respectively. Comparable results were obtained by transient expression in Nicotiana tabacum protoplasts. PEPC of C. glutamicum (PEPC C.g.) in S. tuberosum leaf extracts displays its characteristic K m(PEP) value. Plant growth was examined with plants showing high expression of PEPC and, moreover, with a plant cell line expressing and antisense S. tuberosum (anti-sppc) gene. In axenic culture the growth rate of a cppc plant cell line was appreciably diminished, whereas growth rates of an anti-sppc line were similar or slightly higher than in controls. Malate levels were increased in cppc plants and decreased in antisense plants. There were no significant differences in photosynthetic electron transport or steady state CO2 assimilation between control plants and transformants overexpressing PEPC C.g. or anti-sppc plants. However, a prolonged dark treatment resulted in a delayed induction of photosynthetic electron transport in plants with less PEPC. Rates of CO2 release in the dark determined after a 45 min illumination period at a high proton flux density were considerably enhanced in cppc plants and slightly diminished in anti-sppc plants. When CO2 assimilation rates were corrected for estimated rates of mitochondrial respiration in the light, the electron requirement for CO2 assimilation determined in low CO2 was slightly lower in transformants with higher PEPC, whereas transformants with decreased PEPC exhibited an appreciably elevated electron requirement. The CO2 compensation point remained unchanged in plants (cppc) with high PEPC activity, but might be increased in an antisense plant cell line. Stomatal opening was delayed in antisense plants, but was accelerated in plants overexpressing PEPC C.g. compared to the controls.
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  • 26
    ISSN: 1573-5028
    Keywords: photosystem II ; photosynthesis ; chlorophyll-binding protein ; Synechocystis ; oxygen evolution ; oligonucleotide-mediated mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract CP 47, a component of photosystem II (PSII) in higher plants, algae and cyanobacteria, is encoded by the psbB gene. Site-specific mutagenesis has been used to alter a portion of the psbB gene encoding the large extrinsic loop E of CP 47 in the cyanobacterium Synechocystis 6803. Alteration of a lysine residue occurring at position 321 to glycine produced a strain with altered PSII activity. This strain grew at wild-type rates in complete BG-11 media (480 µM chloride). However, oxygen evolution rates for this mutant in complete media were only 60% of the observed wild-type rates. Quantum yield measurements at low light intensities indicated that the mutant had 66% of the fully functional PSII centers contained in the control strain. The mutant proved to be extremely sensitive to photoinactivation at high light intensities, exhibiting a 3-fold increase in the rate of photoinactivation. When this mutant was grown in media depleted of chloride (30 µM chloride), it lost the ability to grow photoautotrophically while the control strain exhibited a normal rate of growth. The effect of chloride depletion on the growth rate of the mutant was reversed by the addition of 480 µM bromide to the chloride-depleted BG-11 media. In the presence of glucose, the mutant and control strains grew at comparable rates in either chloride-containing or chloride-depleted media. Oxygen evolution rates for the mutant were further depressed (28% of control rates) under chloride-limiting conditions. Addition of bromide restored these rates to those observed under chloride-sufficient conditions. Measurements of the variable fluorescence yield indicated that the mutant assembled fewer functional centers in the absence of chloride. These results indicate that the mutation K321G in CP 47 affects PSII stability and/or assembly under conditions where chloride is limiting.
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  • 27
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    Plant molecular biology 27 (1995), S. 293-306 
    ISSN: 1573-5028
    Keywords: ferredoxin ; PetF gene ; circadian rhythm ; light regulation ; wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A genomic clone encoding the precursor of wheat leaf ferredoxin has been isolated and characterised. The uninterrupted PetF gene encodes a polypeptide of 143 amino acid residues, consisting of an N-terminal presequence of 46 amino acid residues and a mature polypeptide of 97 amino acid residues. Southern blot analysis suggests that six copies of the PetF gene are present in the wheat haploid genome. Northern blot analysis has shown that the genes are both developmentally and light regulated in wheat seedlings and provides evidence that a circadian rhythm regulates the steady-state levels of ferredoxin transcripts. The intact wheat gene and several chimeric constructs, containing portions of the 5′-upstream region fused to the β-glucuronidase reporter gene, have been introduced into tobacco plants, but levels of β-glucuronidase activity above background were not detected, suggesting that the 5′-upstream region is unable to function as a promoter in tobacco plants.
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  • 28
    ISSN: 1573-5028
    Keywords: chloroplasts ; gene expression ; heat bleaching ; photosynthesis ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A shift in the ratio of chlorophyll (Chl) a and Chl b is an early indicator of heat bleaching in Euglena gracilis. This observation prompted us to consider whether or not changes in steady-state levels of chloroplast transcripts and in transcriptional activity could limit the synthesis of Chl a-binding proteins in bleaching plastids. We found that the mature transcripts for CP47 and CP43, the Chl a-binding apoproteins of the proximal antenna of photosystem II, decline sharply very early during bleaching. Our study also shows that transcription of psbB and psbC, the chloroplast genes encoding CP47 and CP43, remains essentially unchanged during the same interval. We conclude that posttranscriptional events, such as mRNA stability, could play a major role in initiating an irreversible loss of chloroplast function in Euglena at a moderately elevated temperature. Lack of these transcripts would eventually impair the assembly of photosystem II in thylakoids.
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  • 29
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    Plant molecular biology 30 (1996), S. 673-677 
    ISSN: 1573-5028
    Keywords: cDNA sequence ; chymotrypsin inhibitor ; histidine-tag ; protein Z ; serpin ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A full-length clone encoding the wheat (Triticum aestivum L.) serpin WSZ1 was isolated from a cDNA library based on mRNA from immature grain. The 398 amino acid sequence deduced from the cDNA was corroborated by sequencing CNBr peptides of WSZ1 purified from resting grain. WSZ1 belongs to the subfamily of protein Z-type serpins and the amino acid sequence is 70% identical with the barley serpins BSZ4 and BSZx and 27–33% identical with human serpins such as α1-proteinase inhibitor, antithrombin III, and plasminogen activator inhibitor. The cDNA was subcloned in the pET3d expression vector, equipped with a histidine affinity tag at the N-terminus and expressed in Escherichia coli BL(21) DE3 pLysS. Recombinant WSZ1 from the soluble fraction was partially purified on Ni-NTA agarose and MonoQ columns and shown to form SDS-stable complexes with α-chymotrypsin. Southern blots and amino acid sequencing indicated that only few serpins are encoded by wheat, but at least three distinct genes are expressed in the grain. Cleavage experiments on a chymotrypsin column suggested a Gln-Gln reactive site bond not previously observed in inhibitory serpins.
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  • 30
    ISSN: 1573-5028
    Keywords: Cyanobacteria ; gene copy number ; light regulation ; photosynthesis ; photosystem II reaction center ; polymerase chain reaction ; psbA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract DNA sequence, copy number, expression and phylogenetic relevance of the psbA gene from the abundant marine prokaryote P. marinus CCMP 1375 was analyzed. The 7 amino acids near the C-terminus missing in higher plant and in Prochlorothrix hollandica D1 proteins are present in the derived amino acid sequence. P. marinus contains only a single psbA gene. Thus, this organism lacks the ability to adapt its photosystem II by replacement of one type of D1 by another, as several cyanobacteria do. Phylogenetic trees suggested the D1-1 iso-form from Synechococcus PCC 7942 as the next related D1 protein and place P. Marinus separately from Prochlorothrix hollandica among the cyanobacteria.
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  • 31
    ISSN: 1573-5028
    Keywords: chlorophyll synthesis ; cyanobacteria ; chlorophyl-binding proteins ; photosynthesis ; thylakoid membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Part of the chlL gene encoding a component involved in light-independent protochlorophyllide reduction was deleted in wild type and in a photosystem I-less strain of Synechocystis sp. PCC 6803. In resulting mutants, chlorophyll biosynthesis was fully light-dependent. When these mutants were propagated under light-activated heterotrophic growth conditions (in darkness except for 15 min of weak light a day) for several weeks, essentially no chlorophyll was detectable but protochlorophyllide accumulated. Upon return of the chlL - mutant cultures to continuous light, within the first 6 h chlorophyll was synthesized at the expense of protochlorophyllide at a rate independent of the presence of photosystem I. Chlorophyll biosynthesized during this time gave rise to a 685 nm fluorescence emission peak at 77 K in intact cells. This peak most likely originates from a component different from those known to be directly associated with photosystems II and I. Development of 695 and 725 nm peaks (indicative of intact photosystem II and photosystem I, respectively) required longer exposures to light. After 6 h of greening, the rate of chlorophyll synthesis slowed as protochlorophyllide was depleted. In the chlL - strain, greening occurred at the same rate at two different light intensities (5 and 50 μE m-2s-1), indicating that also at low light intensity the amount of light is not rate-limiting for protochlorophyllide reduction. Thus, in this system the rate of chlorophyll biosynthesis is limited neither by biosynthesis of photosystems nor by the light-dependent protochlorophyllide reduction. We suggest the presence of a chlorophyll-binding ‘chelator’ protein (with 77 K fluorescence emission at 685 nm) that binds newly synthesized chlorophyll and that provides chlorophyll for newly synthesized photosynthetic reaction centers and antennae.
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  • 32
    ISSN: 1573-5028
    Keywords: Cyanobacteria ; photosynthesis ; random mutagenesis ; sodium bisulfite ; thylakoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To identify amino acid residues of the D2 protein that are critical for functional photosystem II (PS II), sodium bisulfite was utilized for in vitro random mutagenesis of the psbDI gene from Synechocystis sp. PCC 6803. Sodium bisulfite reacts specifically with cytosine in single-stranded regions of DNA and does not attack double-stranded DNA. Using a hybrid plasmid that was single-stranded in the region to be mutagenized and that was double-stranded elsewhere, mutations were targeted to a specific psbDI region coding for the lumenal A-B loop of the D2 protein. Several mutants were isolated with a total of 15 different amino acid changes in the loop. The majority of these mutations did not result in a loss of photoautotrophic growth or in significantly altered PS II function. However, mutation of Glu-69 to Lys, Ser-79 to Phe, and Ser-88 to Phe were found to influence photosystem II activity; the importance of the latter two residues for proper PS II function was unexpected. Cells carrying the double mutation S79F/S88F in D2 did not grow photoautotrophically and had no functionally active PS II centers. The single mutant S79F was also incapable of photoautrophic growth, but displayed reasonably stable oxygen evolution, while PS II function in the single mutant S88F appeared to be close to normal. Because of the more pronounced phenotype of the S79F/S88F strain as compared to the single mutants, both Ser residues appear to affect stable assembly and function of the PS II complex. The mechanism by which the S79F mutant loses photoautotrophic growth remains to be established. However, these results show the potential of targeted random mutagenesis to identify functionally important residues in selected regions of proteins.
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  • 33
    ISSN: 1573-5028
    Keywords: differential display ; HSP70 gene family ; 3′ non-coding region ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have modified the differential display technique to isolate 3′ regions from different members of the wheat HSP70 gene family. An HSP70 gene family-specific degenerate primer was used as a 5′ primer in place of the arbitrary primer used in the original technique. We cloned and sequenced three cDNA fragments that were differentially expressed in heat stressed wheat seedlings. Based on the high similarity between predicted translation products of these three sequences and known members of the HSP70 family from plants, these cDNAs were identified as members of the HSP70 gene family. Two of these members appeared distinct in the 3′ non-coding region with only 48% identity. Therefore differential display could successfully be used to isolate 3′ regions of different members of a multigene family in a relatively short period, even if the members had highly similar protein-coding regions.
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  • 34
    ISSN: 1432-203X
    Keywords: Abscisic acid ; Anther culture ; Light ; Metallothionein ; Pollen embryogenesis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cloned cDNA to the wheat (Triticum aestivum) early cysteine-labeled metallothionein has many characteristics of a molecular marker for pollen embryogenesis in this plant. This transcript was not detected in uninucleate microspores at the time of culture or in pollen at any stage during normal ontogeny; its mRNA did begin to increase in embryogenic microspores within 6 h of culture, peaked at around 24 h, declined, then leveled off through the 21-day-old embryoid stage. Additionally, the accumulation of the embryoid-abundant EcMt gene transcript showed a direct and positive correlation with an increase of ABA in embryogenic microspores and developing pollen embryoids. Irradiating cultures with high intensity white light or with far-red, or blue light, suppressed EcMt transcript accumulation and the ability of microspores to form embryoids; however, light did not affect ABA concentrations during the early stages of culture. These results suggest that although a promoter of pollen embryogenesis in bread wheat, ABA alone cannot maintain the sporophytic differentiation of microspores subjected to inhibitory regimes of light in vitro. Whether or not light acts directly or indirectly in suppressing EcMt gene expression and pollen embryogenesis remains unknown.
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  • 35
    ISSN: 1432-203X
    Keywords: Key words Bread wheat ; Triticum aestivum ; Tritordeum ; Tissue electroporation ; Transient gene expression
    Source: Springer Online Journal Archives 1860-2000
    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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  • 36
    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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  • 37
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    Theoretical and applied genetics 91 (1995), S. 618-626 
    ISSN: 1432-2242
    Keywords: Comparative maps ; Deletion lines ; Molecular-tagged chromosome regions (MTCRs) ; Triticum aestivum ; Hordeum vulgare
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Comparative genetic maps among the Triticeae or Gramineae provide the possibility for combining the genetics, mapping information and molecular-marker resources between different species. Dense genetic linkage maps of wheat and barley, which have a common array of molecular markers, along with deletion-based chromosome maps of Triticum aestivum L. will facilitate the construction of an integrated molecular marker-based map for the Triticeae. A set of 21 cDNA and genomic DNA clones, which had previously been used to map barley chromosome 1 (7H), were used to physically map wheat chromosomes 7A, 7B and 7D. A comparative map was constructed to estimate the degree of linkage conservation and synteny of chromosome segments between the group 7 chromosomes of the two species. The results reveal extensive homoeologies between these chromosomes, and the first evidence for an interstitial inversion on the short arm of a barley chromosome compared to the wheat homoeologue has been obtained. In a cytogenetically-based physical map of group 7 chromosomes that contain restriction-fragment-length polymorphic DNA (RFLP) and random amplified polymorphic DNA (RAPD) markers, the marker density in the most distal third of the chromosome arms was two-times higher than in the proximal region. The recombination rate in the distal third of each arm appears to be 8–15 times greater than in the proximal third of each arm where recombination of wheat chromosomes is suppressed.
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  • 38
    ISSN: 1432-2242
    Keywords: Key wordsSuppressor gene ; Powdery mildew resistance ; Gene location ; Triticum aestivum ; Secale cereale ; Monosomic analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The chromosomal location of a suppressor for the powdery mildew resistance genes Pm8 and Pm17 was determined by a monosomic set of the wheat cultivar Caribo. This cultivar carries a suppressor gene inhibiting the expression of Pm8 in cv Disponent and of Pm17 in line Helami-105. In disease resistance assessments, monosomic F1 hybrids (2n=41) of Caribo × Disponent and Caribo × Helami-105 lacking chromosome 7D were resistant, whereas monosomic F1 hybrids involving the other 20 chromosomes, as well as disomic F1 hybrids (2n=42) of all cross combinations, were susceptible revealing that the suppressor gene for Pm8 and Pm17 is localized on chromosome 7D. It is suggested that genotypes without the suppressor gene be used for the exploitation of genes Pm8 and Pm17 in enhancing powdery mildew resistance in common wheat.
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  • 39
    ISSN: 1432-2242
    Keywords: Haynaldia villosa ; Triticum aestivum ; C-banding ; Genomic in situ hybridization ; Alien chromosome addition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genomic in situ hybridization (GISH) offers a convenient and effective method for cytological detection, but can not determine the identity of the chromosomes involved. We integrated C-banding with GISH to identify Haynaldia villosa chromosomes in a wheat background. All chromosomes of H. villosa showed C-bands, either in telomeric regions or in both telomeric and centromeric regions, which allowed unequivocal identification of each H. villosa chromosome. The seven pairs of H. villosa chromosomes were differentiated as 1–7 according to their characteristic C-bands. Using a sequential C-banding and GISH technique, we have analyzed somatic cells of F3 plants from the amphiploid Triticum aestivum-H. villosa x ‘Yangmai 158’ hybrids. Three plants (94009/5-4,94009/5-8 and 94009/5-9) were shown to contain H. villosa chromosome(s). 94009/5-4 (2n = 45) had three H. villosa chromosomes (2, 3 and 4); 94009/5-8 (2n = 45) possessed one chromosome 4 and a pair of chromosome 5, and 94009/5-9 (2n = 43) was found to have one chromosome 6 of H. villosa. The combination of GISH with C-banding described here provides a direct comparison of the cytological and molecular landmarks. Such a technique is particularly useful for identifying and localizing alien chromatin and DNA sequences in plants.
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  • 40
    ISSN: 1432-2242
    Keywords: Triticum timopheevii ; Triticum aestivum ; Chromosome substitution ; C-banding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Whether the two tetraploid wheat species, the well known Triticum turgidum L. (macaroni wheat, AABB genomes) and the obscure T. timopheevii Zhuk. (AtAtGG), have monophyletic or diphyletic origin from the same or different diploid species presents an interesting evolutionary problem. Moreover, T. timopheevii and its wild form T. araraticum are an important genetic resource for macaroni and bread-wheat improvement. To study these objectives, the substitution and genetic compensation abilities of individual T. timopheevii chromosomes for missing chromosomes of T. aestivum ‘Chinese Spring’ (AABBDD) were analyzed. ‘Chinese Spring’ aneuploids (nullisomic-tetrasomics) were crossed with a T. timopheevii x Aegilops tauschii amphiploid to isolate T. timopheevii chromosomes in a monosomic condition. The F1 hybrids were backcrossed one to four times to Chinese Spring aneuploids without selection for the T. timopheevii chromosome of interest. While spontaneous substitutions involving all At- and G-genome chromosomes were identified, the targeted T. timopheevii chromosome was not always recovered. Lines with spontaneous substitutions from T. timopheevii were chosen for further backcrossing. Six T. timopheevii chromosome substitutions were isolated: 6At (6A), 2G (2B), 3G (3B), 4G (4B), 5G (5B) and 6G (6B). The substitution lines had normal morphology and fertility. The 6At of T. timopheevii was involved in a translocation with chromosome 1G, resulting in the transfer of the group-1 gliadin locus to 6At. Chromosome 2G substituted for 2B at a frequency higher than expected and may carry putative homoeoalleles of gametocidal genes present on group-2 chromosomes of several alien species. Our data indicate a common origin for tetraploid wheat species, but from separate hybridization events because of the presence of a different spectrum of intergenomic translocations.
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  • 41
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    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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  • 42
    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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  • 43
    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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  • 44
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    Theoretical and applied genetics 92 (1996), S. 666-672 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Puccinia striiformis ; Diversity ; Competition ; Path analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four club wheat cultivars and three two-component cultivar mixtures, planted at five frequencies, were grown in three environments in both the presence and absence of stripe rust. The effect of stripe rust on wheat yield was through the yield components, with weight of individual seed being the component most affected by rust. In some cases, yield component compensation was indicated by the presence of negative correlations among the yield components. Path analysis of the yield components revealed that components with the highest correlations to yield also had the largest direct effects on yield. Of the yield components, number of heads per unit area exerted the largest direct influence on yield. The direct effects of number of seeds per head and weight of individual seed were similar, although number of seeds per head was more important in the absence of rust than in its presence. The pure stands and mixtures differed considerably with respect to correlation coefficients, but were very similar for direct effects of yield components on yield. Most of these discrepancies were due to opposing indirect effects, which were not evident from correlation coefficients alone.
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  • 45
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    Theoretical and applied genetics 90 (1995), S. 1158-1163 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Puccinia graminis ; Aneuploid ; Cytogenetics ; Monosomics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The chromosomal locations of genes for resistance to stem rust (Puccinia graminis Pers.: Pers. f. sp. tritici Eriks. & E. Henn.) in the wheat (Triticum aestivum L.) cultivar ‘Waldron’ (WDR) were determined by monosomic analyses. Wheat lines WDR-B1, -C2, -E4, and -F1,which have single genes for resistance to stem rust derived previously from WDR sel. ‘Little Club’, were crossed onto a complete set of 21 ‘Chinese Spring’ monosomics. The F2 and backcross-F1 (BC1F1) seedlings from each of the 84 crosses were tested for reaction to culture 111-SS2 (CRL-LCBB) of stem rust, and a few selected segregants were analyzed cytologically for chromosome number. The F2 from 2 crosses of WDR-C2, -E4 and -F1 and the BC1F1 from 2 crosses of WDR-F1 were tested also with culture Or11c (CRL-QBCN). Significant deviations from disomic ratios towards monosomic ratios in the F2 and BC1F1 were used to determine which chromosomes carried the genes for resistance. Cytological analyses of certain BC1F1 and susceptible F2 plants were used to help identify the location of the genes for rust resistance. WDR-B1 has a gene, herein designated Sr41, for resistance on chromosome 4D. WDR-C2 has a gene on chromosome 7 A that may be the same as one previously designated SrWld2. WDR-E4 has a gene on chromosome 2A, possibly SrWld1, which is effective against most or all North American stem rust cultures. WDR-F1 has a gene on chromosome 6B that is the same as or similar to Sr11.
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  • 46
    ISSN: 1432-2242
    Keywords: Suppressor gene ; Powdery mildew resistance ; Gene location ; Triticum aestivum ; Secale cereale ; Monosomic analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The chromosomal location of a suppressor for the powdery mildew resistance genes Pm8 and Pm17 was determined by a monosomic set of the wheat cultivar Caribo. This cultivar carries a suppressor gene inhibiting the expression of Pm8 in cv Disponent and of Pm17 in line Helami-105. In disease resistance assessments, monosomic F1 hybrids (2n=41) of Caribo x Disponent and Caribo x Helami-105 lacking chromosome 7D were resistant, whereas monosomic F1 hybrids involving the other 20 chromosomes, as well as disomic F1 hybrids (2n=42) of all cross combinations, were susceptible revealing that the suppressor gene for Pm8 and Pm17 is localized on chromosome 7D. It is suggested that genotypes without the suppressor gene be used for the exploitation of genes Pm8 and Pm17 in enhancing powdery mildew resistance in common wheat.
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  • 47
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; HMW glutenin genes ; Unequal crossing-over ; PCR ; Glu-D1 locus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract High-molecular-weight (HMW) glutenin subunits are a particular class of wheat endosperm proteins containing a large repetitive domain flanked by two short N- and C-terminal non-repetitive regions. Deletions and insertions within the central repetitive domain has been suggested to be mainly responsible for the length variations observed for this class of proteins. Nucleotide sequence comparison of a number of HMW glutenin genes allowed the identification of small insertions or deletions within the repetitive domain. However, only indirect evidence has been produced which suggests the occurrence of substantial insertions or deletions within this region when a large variation in molecular size is present between different HMW glutenin subunits. This paper represents the first report on the molecular characterization of an unusually large insertion within the repetitive domain of a functional HMW glutenin gene. This gene is located at the Glu-D1 locus of a hexaploid wheat genotype and contains an insertion of 561 base pairs that codes for 187 amino acids corresponding to the repetitive domain of a HMW glutenin subunit encoded at the same locus. The precise location of the insertion has been identified and the molecular processes underlying such mutational events are discussed.
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  • 48
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    Theoretical and applied genetics 93 (1996), S. 1066-1070 
    ISSN: 1432-2242
    Keywords: Amylose synthesis ; Aneuploid ; Granule-bound starch synthase ; Triticum aestivum ; Wx gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Amylose synthesis in wheat endosperm is mainly controlled by the granule-bound starch synthase of about 60 kDa, the so-called waxy (Wx) protein. The Wx proteins are the product of the Wx genes at a triplicate set of single-copy homoeoloci located on chromosomes 7A (Wx-A1), 4A (Wx-B1) and 7D (Wx-D1). Using ‘Chinese Spring’ and its aneuploid lines, including nullisomic-tetrasomics, tetrasomics, ditelosomics and deletion stocks, together with single-chromosome substitution lines for these chromosomes, the effects of varying the dosage of whole chromosomes and chromosome arms, as well as the effects of null alleles, upon amylose synthesis were investigated. Nullisomic 4A and the deletion of chromosome segments carrying the Wx-B1 gene reduced the amylose content by more than 3%. A reasonable agreement was found in the substitution lines. This confirms that the absence of the Wx-B1 gene, or else substitution of this gene by its null allele, has the most striking effect on decreasing amylose synthesis. The removal of chromosomes carrying either the Wx-A1 or the Wx-D1 gene reduces the amylose content by less than 2%. A similar reduction was revealed by substitution of these two genes by the null alleles. Double dosages of chromosomes 7A, 4A and 7D did not increase amylose content, while the tetrasomic chromosomes produced more of the respective Wx proteins. This suggests that a certain level of Wx gene activity or of the Wx proteins led to the maximum amount of amylose.
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  • 49
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    Theoretical and applied genetics 93 (1996), S. 1112-1118 
    ISSN: 1432-2242
    Keywords: Genetic map ; RFLP ; RAPD ; Secale cereale ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A genetic map of six chromosomes of rye, (all of the rye chromosomes except for 2R), was constructed using 77 RFLP and 12 RAPD markers. The map was developed using an F2 population of 54 plants from a cross between two inbred lines. A rye genomic library was constructed as a source of clones for RFLP mapping. Comparisons were made between the rye map and other rye and wheat maps by including additional probes previously mapped in those species. These comparisons allowed (1) chromosome arm orientation to the linkage groups to be given, (2) the corroboration of several evolutionary translocations between rye chromosomes and homoeologous chromosomes of wheat; (3) an increase in the number of available markers for target regions of rye that show colinearity with wheat. Inconsistencies in the location of markers between the wheat and rye maps were mostly detected by multi-copy probes.
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  • 50
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    Theoretical and applied genetics 93 (1996), S. 1078-1082 
    ISSN: 1432-2242
    Keywords: Allele-specific PCR (AS-PCR) ; Powdery mildew ; Hordeum vulgare ; Triticum aestivum ; Sequence-tagged site (STS)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Primers for the polymerase chain reaction (PCR) were tailored to selectively amplify RFLP marker alleles associated with resistance and susceptibility for powdery mildew in cereals. The differentiation between marker alleles for susceptible and resistant genotypes is based on the discrimination of a single nucleotide by using allele-specific oligonucleotides as PCR primers. The PCR assays developed are diagnostic for RFLP alleles at the loci MWG097 in the barley genome and Whs350 in the wheat genome. The first marker locus is closely linked to MlLa resistance in barley, while the latter is linked to Pm2 resistance locus in wheat. PCR analysis of 31 barley and 30 wheat cultivars, with some exceptions, verified the presence or absence of the resistance loci investigated. These rapid PCR-based approaches are proposed as an efficient alternative to conventional procedures for selecting powdery mildew-resistant genotypes in breeding programs.
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  • 51
    ISSN: 1432-2242
    Keywords: Key words Genetic resources ; Dynamic conservation ; Two-dimensional electrophoresis ; Artificial population ; Triticum aestivum
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    Notes: Abstract  Dynamic management of genetic resources aims to conserve genetic variability between different populations evolving in contrasting environments. It is thus of importance to determine whether differences appearing between populations are stochastic or if they come about from adaptation. Two-dimensional electrophoresis (2DE) was used to study genetic differentiation of 11 wheat populations evolving since 1984 in a multi-site network covering the major cultivation area of wheat in France. Gels were scanned and protein-spot intensities were measured through image analysis. As it was not possible to assay each individual, populations were characterized using pooled extracts from several plants. In the first step, two parents among the 16 parental lines involved in the initial wheat composite-cross population were exhaustively studied to identify a set of polymorphic spots against which the entire set of evolved populations could be compared. This analysis confirmed the efficiency of gel image-processing to determine the composition of pooled extracts. Of the 48 spots used to investigate population differentiation, 15 showed significant differences at the P〈0.05 level. Populations that evolved independently at the same location showed similar differentiation, even when their cultivation methods were different. These results suggest that natural selection acted strongly on the evolution of the populations, and that responses to selection were determined primarily by macro-environmental conditions.
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  • 52
    ISSN: 1432-2242
    Keywords: Key words Wheat landrace ; Triticum aestivum ; Powdery mildew resistance ; Monosomic analysis ; Gene location
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Chinese wheat landrace Chiyacao exhibited a response pattern different from that of the cultivars/lines possessing documented Pm genes after inoculation with 106 isolates of Erysiphe graminis f. sp. tritici. To characterize this resistance and to determine the chromosomal location of the gene or genes present, we crossed the landrace to susceptible cultivar ‘Chinese Spring’ and also to a set of 21 ‘Chinese Spring’ monosomic lines. Monosomic F1 plants were allowed to self-pollinate and to produce F2 seeds. Seedlings of F2 plants and their parents were inoculated with isolates nos. 5 and 12 of Erysiphe graminis f. sp. tritici. The results revealed that one major dominant gene is located on chromosome 6D of Chinese common wheat landrace Chiyacao. The new gene is designated Pm 24.
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  • 53
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    Theoretical and applied genetics 95 (1997), S. 1300-1304 
    ISSN: 1432-2242
    Keywords: Key words Flow cytometry ; Triticum aestivum ; DNA analysis ; Monosomics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Two complete, independently maintained sets of 21 monosomic wheat lines derived from cv. ‘Chinese Spring’ were analyzed for their DNA content at the G1 stage with flow cytometry. The DNA content of individual chromosomes was estimated by subtracting the value of a monosomic line from that of euploid wheat. Our data show that the estimated 2C DNA of individual wheat chromosomes in 21 monosomics at the G1 stage ranges from about 0.58 pg in chromosome 1D to approximately 1.12 pg in chromosome 3A. The A genome (2C=6.15 pg) seems to contain more DNA than the B (2C=6.09 pg) and D (2C=5.05 pg) genomes. Analysis of variance showed significant differences (α=0.01) in DNA content both among homoeologous groups and among genomes. Our estimates of interphase DNA content of wheat chromosomes from monosomic lines were poorly correlated to the chromosome sizes at metaphase (r=0.622, P≤0.01). This poor correlation might be due to differential coiling among chromosomes during cell division, possible bias of fluorochrome binding to heterochromatin, or heterogeneity among monosomic lines. Finally, flow cytometry may aid but cannot replace cytological checks in aneuploid maintenance.
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  • 54
    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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  • 55
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    Theoretical and applied genetics 94 (1997), S. 472-479 
    ISSN: 1432-2242
    Keywords: Key words Genetic diversity ; RFLP ; Coefficient of parentage ; Triticum aestivum ; Gene pool
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Genetic diversity in a set of 11 red and 11 white wheat lines from the Eastern U.S. soft wheat germplasm pool was measured using restriction fragment length polymorphism (RFLP) assay and coefficients of parentage (COP) analysis. On average, 78% of all bands revealed by three enzymes with 48 RFLP clones were monomorphic. Average pairwise genetic similarity (GS) was 0.97 when data from all enzymes were pooled. Probe Polymorphic Information Content (PIC) indexes ranged from 0 to 0.73 with a mean of 0.2. Fewer than 55% of the probes revealed any polymorphism. The frequency of polymorphism in the Eastern U.S. soft white winter (SWW) wheat gene pool was much lower than that observed in the Eastern U.S. soft red winter (SRW) wheat gene pool. SWW lines formed a single group on a dendrogram based on cluster analysis of RFLP-derived GS estimates, while SRW lines did not form a single group. COP values for all pairs of the Eastern U.S. soft wheat lines ranged from 0.02 to 0.9 with a mean of 0.21. SWW wheat lines traced to 53 ancestral lines and had an average COP of 0.51. The SRW wheat gene pool had more complex parentages (mean COP=0.15 and a total of 65 ancestral lines). COPs were correlated with RFLP-based GS for all line pairs (r=0.73, P〈0.01). However, correlations between the two similarity measures were substantially lower when the SRW and SWW wheat gene pools were considered individually (r values of 0.23 and 0.28, respectively). The actual GS among unrelated lines in the U.S. Eastern soft wheat gene pool appears to be higher than that observed for unrelated landraces from Southwest Asia (0.96 vs. 0.905), suggesting that the ancestral landrace parents of this gene pool were themselves drawn from a base population where inbreeding, i.e., F, was greater than zero.
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  • 56
    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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  • 57
    ISSN: 1432-2242
    Keywords: Key words Aegilops markgrafii ; Triticum aestivum ; RAPD ; Addition lines ; Leaf rust ; Powdery mildew
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Aegilops markgrafii contains resistance genes to powdery mildew, leaf rust and stripe rust, and also has high crude protein and lysine contents, which can be useful for wheat improvement. These important traits are localized on different chromosomes. Disomic Triticum aestivum-Ae. markgrafii addition lines and euploid introgression lines showing leaf-rust and powdery mildew resistance were screened with RAPDs to detect chromosome-specific markers which can accelerate the breeding process. RAPD markers for all six available disomic addition lines were obtained. The additional chromosomes B, C, D, E, F and G were identified by three, three, three, two, one and seven primers, respectively. All three chromosome-B-specific RAPD markers demonstrated the presence of alien chromatin in the leaf-rust-resistant 42-chromosome introgression lines as well as in the segregating progeny. The three chromosome-C-identifying primers also demonstrated the presence of that chromosome in powdery mildew-resistant euploid introgression lines. The substitution lines (5A)5C and (5D)5C with different genetic backgrounds for both parents, in comparison to the lines mentioned above, showed the chromosome C-specific band with only two of the three primers. The chromosome F-specific primer and a primer evident on all the Ae. markgrafii chromosomes analysed did not generate the expected fragments on the chromosome Fdel addition line, indicating that the markers are located on the deleted part of chromosome F.
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  • 58
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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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  • 59
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    Theoretical and applied genetics 90 (1995), S. 1164-1168 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Puccinia graminis ; Allelism ; Inheritance ; Segregation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Triticum aestivum L. cultivar ‘Waldron’ has long lasting resistance to most North American stem rust (Puccinia graminis Pers.:Pers. f. sp. tritici Eriks. and E. Henn.) isolates. The objective of this research was to develop wheat lines monogenic for resistance to stem rust from ‘Waldron’ using allelism tests and tests for reaction to a series of ten stem rust cultures having a range of virulences. Twelve lines homozygous for single resistance genes were selected as parents of a diallel cross to test for allelism among genes for resistance. We identified 6 lines or groups of lines (WDR-A1, the WDR-B1 and WDR-B2 group, the WDR-C1 and WDR-C2 group, WDR-D1, the WDR-E1, WDR-E2, WDR-E3, and WDR-E4 group, and WDR-F1) that carried different single genes for resistance from ‘Waldron’. A seventh line (WDR-G1) probably has two genes for resistance, one in common with WDR-C1 and WDR-C2. The gene in the WDR-E group is probably the same as SrWld1, and the one in WDR-F1 the same as Sri11. ‘Waldron’ probably has two or more genes for resistance to stem rust that previous genetic studies did not detect.
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  • 60
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    Theoretical and applied genetics 91 (1995), S. 780-782 
    ISSN: 1432-2242
    Keywords: Physical mapping ; RFLP ; Cereals ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cytologically based physical maps for the group 3 chromosomes of wheat were constructed by mapping 25 Triticum aestivum deletion lines with 29 T. tauschii and T. aestivum RFLP probes. The deletion lines divide chromosomes 3A, 3B, and 3D into 31 discrete intervals, of which 18 were tagged by marker loci. The comparison of the consensus physical map with a consensus RFLP linkage map of the group 3 chromosomes of wheat revealed a fairly even distribution of marker loci on the long arm, and higher recombination in the distal region.
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  • 61
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    Theoretical and applied genetics 92 (1996), S. 163-169 
    ISSN: 1432-2242
    Keywords: Bread wheat ; Triticum aestivum ; Culture medium ; Embryogenic callus ; Plant regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Forty-eight bread wheat (Triticum aestivum L.) released cultivars and elite advanced lines were evaluated for their ability to produce embryogenic callus using three different media. Basal N6 medium supplemented with dicamba (E1), MS medium containing 2,4-D (E3) or MS medium containing 2,4-D plus different amino acids (E5) were used for callus initiation and maintenance. Plant regeneration was achieved on basal MS medium with indole-3-acetic acid (IAA) and 6-benzylamino purine (BAP) and rooting on MS with 1-naphthaleneacetic acid (NAA). Percentage regeneration varied widely with both genotype and initiation medium, with values ranging from 2% to 94%. The number of plantlets produced per embryo ranged from 6 to 42. Thirteen genotypes showed at least 50% regeneration after culture on E5 medium; 3 genotypes after culture on E3 initiation medium and 1 after initiation on E1. After four subcultures, over a 16-week period, 41 genotypes (85%) lost their ability to regenerate plants while the remaining 7 lines (15%) retained plant regeneration potential but at reduced levels. E3 medium was found to be the best for maintaining regeneration potential after four subcultures.
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  • 62
    ISSN: 1432-2242
    Keywords: Wheat ; Triticum aestivum ; Triticum peregrinum ; Chromosome addition lines ; RFLPs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Analyses of RFLPs, isozymes, morphological markers and chromosome pairing were used to isolate 12 Triticum aestivum cv Chinese Spring (genomes A, B, and D)-T. peregrinum (genomes Sv and Uv) disomic chromosome addition lines. The evidence obtained indicates that each of the 12 lines contains an intact pair of T. peregrinum chromosomes. One monosomic addition line, believed to contain an intact 6Sv chromosome, was also isolated. A CS-7Uv chromosome addition line was not obtained. Syntenic relationships in common with the standard Triticeae arrangement were found for five of the seven Sv genome chromosomes. The exceptions were 4Sv and 7Sv. A reciprocal translocation exists between 4S1 and 7S1 in T. longissimum and evidence was obtained that the same translocation exists in T. peregrinum. In contrast, evidence for syntenic relationships in common with the standard Triticeae arrangements were found for only one Uv chromosome of T. peregrinum.; namely, chromosome 2Uv. All other Uv genome chromosomes are involved in at least one translocation, and the same translocations were found in the U genome of T. umbellulatum. Evidence was also obtained indicating that the centromeric regions of 4U and 4Uv are homoeologous to the centromeric regions of Triticeae homoeologous group-6 chromosomes, that the centromeric regions of 6U and 6Uv are homoeologous to the centromeric regions of group-4 chromosomes, and that 4U and 4Uv are more closely related overall to Triticeae homoeologous group-6 chromosomes than they are to group-4 chromosomes.
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  • 63
    ISSN: 1432-2242
    Keywords: Key words  Wheat ; Triticum aestivum ; Triticum peregrinum ; Chromosome addition lines ; RFLPs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract   Analyses of RFLPs, isozymes, morphological markers and chromosome pairing were used to isolate 12 Triticum aestivum cv Chinese Spring (genomes A, B, and D)-T. peregrinum (genomes Sv and Uv) disomic chromosome addition lines. The evidence obtained indicates that each of the 12 lines contains an intact pair of T. peregrinum chromosomes. One monosomic addition line, believed to contain an intact 6Sv chromosome, was also isolated. A CS-7Uv chromosome addition line was not obtained. Syntenic relationships in common with the standard Triticeae arrangement were found for five of the seven Sv genome chromosomes. The exceptions were 4Sv and 7Sv. A reciprocal translocation exists between 4Sl and 7Sl in T. longissimum and evidence was obtained that the same translocation exists in T. peregrinum. In contrast, evidence for syntenic relationships in common with the standard Triticeae arrangements were found for only one Uv chromosome of T. peregrinum; namely, chromosome 2Uv. All other Uv genome chromosomes are involved in at least one translocation, and the same translocations were found in the U genome of T. umbellulatum. Evidence was also obtained indicating that the centromeric regions of 4U and 4Uv are homoeologous to the centromeric regions of Triticeae homoeologous group-6 chromosomes, that the centromeric regions of 6U and 6Uv are homoeologous to the centromeric regions of group-4 chromosomes, and that 4U and 4Uv are more closely related overall to Triticeae homoeologous group-6 chromosomes than they are to group-4 chromosomes.
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  • 64
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    Theoretical and applied genetics 93 (1996), S. 1078-1082 
    ISSN: 1432-2242
    Keywords: Key words Allele-specific PCR (AS-PCR) ; Powdery mildew ; Hordeum vulgare ; Triticum aestivum ; Sequence-tagged site (STS)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Primers for the polymerase chain reaction (PCR) were tailored to selectively amplify RFLP marker alleles associated with resistance and susceptibility for powdery mildew in cereals. The differentiation between marker alleles for susceptible and resistant genotypes is based on the discrimination of a single nucleotide by using allele-specific oligonucleotides as PCR primers. The PCR assays developed are diagnostic for RFLP alleles at the loci MWG097 in the barley genome and Whs350 in the wheat genome. The first marker locus is closely linked to MlLa resistance in barley, while the latter is linked to Pm2 resistance locus in wheat. PCR analysis of 31 barley and 30 wheat cultivars, with some exceptions, verified the presence or absence of the resistance loci investigated. These rapid PCR-based approaches are proposed as an efficient alternative to conventional procedures for selecting powdery mildew-resistant genotypes in breeding programs.
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  • 65
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    Theoretical and applied genetics 93 (1996), S. 1066-1070 
    ISSN: 1432-2242
    Keywords: Key words Amylose synthesis ; Aneuploid ; Granule-bound starch synthase ; Triticum aestivum ; Wx gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Amylose synthesis in wheat endosperm is mainly controlled by the granule-bound starch synthase of about 60 kDa, the so-called waxy (Wx) protein. The Wx proteins are the product of the Wx genes at a triplicate set of single-copy homoeoloci located on chromosomes 7A (Wx-A1), 4A (Wx-B1) and 7D (Wx-D1). Using `Chinese Spring' and its aneuploid lines, including nullisomic-tetrasomics, tetrasomics, ditelosomics and deletion stocks, together with single-chromosome substitution lines for these chromosomes, the effects of varying the dosage of whole chromosomes and chromosome arms, as well as the effects of null alleles, upon amylose synthesis were investigated. Nullisomic 4A and the deletion of chromosome segments carrying the Wx-B1 gene reduced the amylose content by more than 3%. A reasonable agreement was found in the substitution lines. This confirms that the absence of the Wx-B1 gene, or else substitution of this gene by its null allele, has the most striking effect on decreasing amylose synthesis. The removal of chromosomes carrying either the Wx-A1 or the Wx-D1 gene reduces the amylose content by less than 2%. A similar reduction was revealed by substitution of these two genes by the null alleles. Double dosages of chromosomes 7A, 4A and 7D did not increase amylose content, while the tetrasomic chromosomes produced more of the respective Wx proteins. This suggests that a certain level of Wx gene activity or of the Wx proteins led to the maximum amount of amylose.
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  • 66
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    Theoretical and applied genetics 93 (1996), S. 1112-1118 
    ISSN: 1432-2242
    Keywords: Key words Genetic map ; RFLP ; RAPD ; Secale cereale ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A genetic map of six chromosomes of rye, (all of the rye chromosomes except for 2R), was constructed using 77 RFLP and 12 RAPD markers. The map was developed using an F2 population of 54 plants from a cross between two inbred lines. A rye genomic library was constructed as a source of clones for RFLP mapping. Comparisons were made between the rye map and other rye and wheat maps by including additional probes previously mapped in those species. These comparisons allowed (1) chromosome arm orientation to the linkage groups to be given, (2) the corroboration of several evolutionary translocations between rye chromosomes and homoeologous chromosomes of wheat; (3) an increase in the number of available markers for target regions of rye that show colinearity with wheat. Inconsistencies in the location of markers between the wheat and rye maps were mostly detected by multi-copy probes.
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  • 67
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    Theoretical and applied genetics 93 (1996), S. 1054-1060 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Rye ; Secale cereale ; 1BL.1RS translocation ; 1AL.1RS translocation ; Gliadin, Electrophoresis ; Erysiphe graminis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A suppressor of resistance to powdery mildew conferred by Pm8 showed complete association with the presence of a storage-protein marker resolved by electrophoresis on SDS-PAGE gels. This marker was identified as the product of the gliadin allele Gli-A1a. The mildewresponse phenotypes of wheats possessing the 1BL.1RS translocation were completely predictable from electrophoretograms. The suppressor, designated SuPm8, was located on chromosome 1AS. It was specific in its suppression of Pm8, and did not affect the rye-derived resistance phenotypes of wheat lines with Pm17, also located in 1RS, or of lines with Pm7.
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  • 68
    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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  • 69
    ISSN: 1432-2242
    Keywords: C-banding ; Genomic in situ hybridization ; Triticum aestivum ; T. umbellulatum ; Chromosome addition and translocation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A standard karyotype and a generalized idiogram of Triticum umbellulatum (syn. Aegilops umbellulata, 2n = 2x = 14) was established based on C-banding analysis of ten accessions of different geographic origin and individual T. umbellulatum chromosomes in T. aestivum — T. umbellulatum chromosome addition lines. Monosomic (MA) and disomic (DA) T. aestivum — T. umbellulatum chromosome addition lines (DA1U = B, DA2U = D, MA4U = F, DA5U = C, DA6U = A, DA7U = E = G) and telosomic addition lines (DA1US, DA1UL, DA2US, DA2UL, DA4UL, MA5US, (+ iso 5US), DA5UL, DA7US, DA7UL) were analyzed. Line H was established as a disomic addition line for the translocated wheat — T. umbellulatum chromosome T2DS·4US. Radiation-induced wheat — T. umbellulatum translocation lines resistant to leaf rust (Lr9) were identified as T40 = T6BL·6BS-6UL, T41 = T4BL·4BS-6UL, T44 = T2DS·2DL-6UL, T47 = ‘Transfer’ = T6BS·6BL-6UL and T52 = T7BL·7BS-6UL. Breakpoints and sizes of the transferred T. umbellulatum segments in these translocations were determined by in situ hybridization analysis using total genomic T. umbellulatum DNA as a probe
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  • 70
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    Theoretical and applied genetics 90 (1995), S. 952-956 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Thinopyrum bessarabicum ; Protein/isozyme markers ; In situ hybridization ; Alien disomic additions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thinopyrum bessarabicum (2n=2x=14, JJ) is a self-fertile salt-tolerant grass species, and its hybridization with Triticum aestivum to achieve the transfer of this attributes has been promoted. For the detection of alien introgression, development of diagnostic markers of Th. bessarabicum chromosomes in the wheat background has emerged as an important aspect in our intergeneric hybridization program. Six proteins/isozymes-high-molecular-weight glutenins, superoxide dismutase, grain esterase, β-amylase, glutamate oxaloacetate transaminase and α-amylase —were identified as positive markers for detecting the presence of Th. bessarabicum chromosomes in the advanced backcross derivatives of T. aestivum/Th. bessarabicum//n* T. aestivum. Fluorescent in situ hybridization further enabled the detection of complete and translocated arms of Th. bessarabicum chromosomes in the T. aestivum background. These diagnostic markers served for tentatively characterizing a distinct set of Th. bessarabicum disomic additions to wheat (2n=44) and have facilitated establishing the homoeology of these added chromosomes.
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  • 71
    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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  • 72
    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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  • 73
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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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  • 74
    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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  • 75
    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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  • 76
    ISSN: 1432-2242
    Keywords: Key words Aegilops ventricosa ; Triticum aestivum ; Mayetiola destructor ; Hessian fly ; Resistance gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A new Hessian fly (Mayetiola destructor) resistance gene from Aegilops ventricosa and its transfer to hexaploid wheat is described. The 4D(4Mv) substitution line H-93-33 derived from the cross [(Triticum turgidum H-1-1×Aegilops ventricosa no. 11)×Triticum aestivum H-10-15] was highly resistant to the Spanish population tested. Resistance seemed to be inherited as a single dominant factor in the F2 generation resulting from a cross of H-93-33 with its susceptible parent (H-10-15). Resistance in Ae. venticosa no. 10 was located on chromosome 4Mv using Mv wheat/Ae. ventricosa addition lines. The resistance gene transferred from Ae. ventricosa no. 11 to H-93-33 (H27) is allelic with respect to that of Ae. ventricosa no. 10 and is non-allelic with respect to the genes H3 and H6 from Monon and Caldwell respectively. The assignment of H27 gene to chromosome 4Mv is further supported by its linkage to a gene encoding isozyme Acph-Mv1, previously located on chromosome 4Mv in the line H-93-33. A new marker from homoeologous chromosome group 4 (Amp-Mv2) present in H-93-33 and the 4Mv addition line is described.
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  • 77
    ISSN: 1432-2242
    Keywords: Key words Wheat ; Triticum aestivum ; Transformation ; Nuclear male sterility ; DNA-integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Nuclear male sterility within Triticum aestivum is considered as the ideal basis for the development of a hybridization system for wheat. We engineered nuclear male sterility in wheat by introducing the barnase gene under the control of tapetum-specific promoters derived from corn and rice. A biolistic-mediated transformation method, based on the use of the poly(ADP-ribose)polymerase inhibitor niacinamide, was set up which enriched for low-copy integrations (1–3 copies). Most of these copies were not linked and segregated in the next generation.
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  • 78
    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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  • 79
    ISSN: 1871-4528
    Keywords: benzylaminopurine ; gibberellic acid ; senescence ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The modifying effects of applying the plant growth regulators (PGRs) benzylaminopurine (BAP), gibberellic acid (GA3) and BAP+GA3 on physiological age were studied. Two experiments with two cultivars, differing in rate of physiological ageing (medium-early Pampeana, medium-late Huinkul) and two storage systems were performed during 1988/89 and 1989/90 in two different potato areas of Argentina. In both seasons seed tubers stored in heaps reached an advanced physiological age at planting, compared with tubers from the cold store. Seed tubers of cv. Pampeana were older than those of Huinkul. compared with control crops, those sprayed with BAP maintained ground cover and photosynthesis for longer, and those sprayed with GA3 for a shorter period. Consequently tuber yield was decreased by GA3 in 1988/89, but in 1989/90 all crops treated with PGRs outyielded the control. BAP could overcome effects of advanced physiological age on crop senescence and tuber yield.
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  • 80
    ISSN: 1871-4528
    Keywords: water stress ; photosynthesis ; stress index ; dry matter partitioning ; tuber quality ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A lysimeter experiment was performed to study the optimal allocation of limited water supply in potatoes. Irrigation regimes equal to 40, 60 and 80% of maximum evapotranspiration (ET) were evenly applied over the crop cycle. Other treatments involved withholding 80 mm of irrigation, based on ET, beginning at each of three designated growth stages (tuber initiation, early and late tuber growth). An irrigated control treatment, restoring the entire ET, was included for comparison. Continuous drought stress reduced photosynthesis as irrigation volumes were reduced. Plant biomass and tuber yield decreased almost proportionally to water consumption, so that WUE was roughly constant. N uptake was highest in the control and in 80% ET treatment. Withholding water during tuberisation severely hindered plant physiological processes and penalized tuber yield. Reductions in photosynthesis, total biomass and yield were the greatest when drought was imposed during tuber initiation. The earliest stress resulted in the lowest WUE and N uptake. A new crop water stress index (SI) was proposed, which combines atmospheric demand for water and canopy temperature.
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  • 81
    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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  • 82
    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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  • 83
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    Journal of plant research 109 (1996), S. 375-380 
    ISSN: 1618-0860
    Keywords: Gravitropism ; Growth direction ; Seminal roots ; Triticum aestivum ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The seminal root system of wheat (Triticum aestivum L.) is composed of the primary seminal root, the first pair of seminal roots, and the second pair of seminal roots, which are known to grow in different directions. The direction of root growth, which can be expressed by ϑ (the angle between the root and the plumb line) and φ (the angle between the root and a vertical plane including the primary seminal root), was studied with special attention to the latter. It was measured on seedlings grown in a small hemispherical soil-filled mesh basket. There were varietal differences in the φ of the first pair of roots (φf) and in the φ of the second pair of roots (φs). (φf) and (φs) were significantly correlated. The mean distance (MD), a measure to evaluate the efficiency of root spacing, was correlated with the difference between (φf) and (φs). Neither experimentally applied low soil water potential nor the excision of the primary seminal root affected φ. When the grain was sown vertically with the tip of the embryo pointing downwards, it was found that the growth movement into a direction different from the plumb line and (φs) was greatly modified. it is suggested that certain internal mechanisms, possibly involving gravitropic reactions, are operating to control the direction of root growth. The significance of root growth direction at the seedling stage is discussed.
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  • 84
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    Protoplasma 193 (1996), S. 204-212 
    ISSN: 1615-6102
    Keywords: Golgi bodies ; Mitochondria ; Plastids ; Symmetrical divisions ; Protophloem sieve elements ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Protophloem sieve elements (PSEs) in roots of wheat (Triticum aestivum L.) are arranged in single vertical files. The number of PSEs within the files increases by symmetrical divisions, which take place after the completion of asymmetrical (formative) divisions and before the initiation of differentiation. The divisions are preceded by well defined pre-prophase bands (PPB) of microtubules, which surround the nucleus in an equatorial position. In the cytoplasmic region between the nuclear surface and the PPB, perinuclear and endoplasmic microtubules were observed. The perinuclear microtubules are considered as part of the developing spindle, while the endoplasmic ones interlink the perinuclear microtubules with the PPB. Dividing cells do not show any signs of incipient differentiation. The first and most reliable indication of a commencing differentiation is provided by the sieve-element plastids that begin to accumulate dense crystalloid inclusions in the very young PSEs. In mature PSEs plastids contain two kinds of crystalloid inclusions, dense and thin, in a translucent stroma. Depending on the plastid-inclusions criterion it was shown that: (a) the PSEs of a given root do not initiate differentiation at exactly the same stage, (b) the developmental sequence extends to a span of 7–9 actively differentiating PSEs arranged in a single vertical file, and (c) each PSE needs about 16–21 h to pass through the whole developmental sequence. In the last two differentiating PSEs of a file, mitochondria were found to be enveloped by single cisternae of ER. The association is temporary as it is lost in the first PSEs with an autolysed lumen. During differentiation, Golgi bodies were abundant and active in producing vesicles involved in cell wall development. Golgi vesicles were also found among the microtubules of the PPB, but no local thickening was observed. Golgi bodies disorganize in the last stages of autolysis and disappear in mature sieve elements.
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  • 85
    ISSN: 1610-7403
    Keywords: Chamaecyparis obtusa Endl. ; photosynthesis ; Pinus densiflora Sieb. et Zucc. ; stomatal conductance ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study was conducted to investigate the potential for modifying drought tolerance of Japanese cypress (Chamaecyparis obtusa Endl.) and Japanese red pine (Pinus densiflora Sieb. et Zucc.). Three-year-old seedlings were controlled for five-months at three different soil water potentials ({ie73-1}). Japanese cypress exposed to high {ie73-2} was able to maintain higher photosynthesis (Phn), transpiration (Tr) and stomatal conductance to H2O (gH2O) in comparison to low {ie73-3} pretreatments, however, there was no significant difference in Phn for Japanese red pine. Soil water potential at the threshold from the maximum to limited Phn was higher in high {ie73-4} pretreatments than in low {ie73-5} pretreatments. Net photosynthesis, Tr and gH2O decreased more rapidly in high {ie73-6} pretreatments than in low {ie73-7} pretreatments. Transpiration decreased more significantly than Phn, thus, resulted in increased water use efficiency. All these factors are likely to result in significant improvements in the drought tolerance. Japanese red pine seems more drought-tolerant than Japanese cypress. Japanese cypress is suitable to soil of −0.05 MPa water potential, and Japanese red pine is suitable to −0.16 MPa and even dryer soils.
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  • 86
    ISSN: 1610-7403
    Keywords: chlorophyll fluorescence ; electron transport ; photorespiration ; photosynthesis ; quantum yield ; tree
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Using attached and detached leaves ofAcer palmatum Thunb. andRhaphiolepsis umbellata Makino, pulse-modulated chlorophyll fluorescence and CO2 exchange were measured. Quantum yield of photosynthesis was determined from the fluorescence parameter(Fm′−Fs)/Fm′, where (Fm′−Fs) was defined as the difference between steady state chlorophyll fluorescence (Fs) and maximum fluorescence (Fm′) elicited by a saturating light pulse. The rate of electron transport through photosystem II (total electron flow) was calculated from the product of quantum yield andA (PFD), whereA is the rate of absorbed photons as given by leaf absorptance, and PFD is the photon flux density at the leaf surface. The rate of electron transport dependant on CO2 uptake (assimilative electron flow) was calculated from the gross photosynthetic rate in a leaf. The difference between the rates of total and assimilative electron transport was denoted as the rate of non-assimilative electron transport which depends on photorespiration and oxygen reduction. Available data provided quantitative information on the rate of non-assimilative electron flow in intact leaves. When leaf photosynthesis ofA. palmatum was measured under sunlight, the rates of total and assimilative electron transport were determined to be approximately 900 and 150 μmol equiv. e/mg Chl·h, respectively. The difference (750 μmol equiv. e/mg Chl·h) was attributed to the activity of non-assimilative electron flow. The ratio of total to assimilative electron flow was found to increase gradually with rising in irradiance. The results suggest that non-assimilative electron flow occurred at much higher rate than assimilative electron flow at high irradiance. Implications of the results are briefly discussed in relation to photosynthesis limitation in tree leaves.
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  • 87
    ISSN: 1573-5125
    Keywords: chlorophyll fluorescence ; nutrient limitation ; phytoplankton ; photosynthesis ; quantum efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 88
    ISSN: 1573-5125
    Keywords: intertidal areas ; photosynthetically active radiation ; photosynthesis ; Tagus estuary ; tides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetically active radiation (PAR) and temperature were measured continuously at the surface of estuarine intertidal sediments in the Tagus estuary, Portugal, along two spring-neap tidal cycles. PAR and temperature were strongly conditioned by the periodic tidal inundation, with large and abrupt variations occurring during flooding and ebbing. PAR levels reaching the sediment surface decreased very rapidly to zero or very low values during most of the daytime immersion. Inundation during high tide had the general effect of attenuating the amplitude of daily temperature fluctuation, with the incoming water usually warmer than the sediment during the night or early morning and cooler during the day. The daily progression of tidal emersion resulted in a clear fortnightly variation in total daily PAR reaching the sediment surface, while both daily mean temperature and mean temperature of diurnal low tide periods failed to exhibit a well-defined fortnightly periodicity. The obtained results indicate that the estuarine intertidal environment is dominated, at sub-seasonal time scales, by fortnightly periodicity in irradiance and temperature conditions favourable for benthic photosynthesis.
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  • 89
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    Journal of applied phycology 10 (1998), S. 547-554 
    ISSN: 1573-5176
    Keywords: herbicide ; green alga ; growth ; nutrients ; photosynthesis ; it Protosiphon botryoides ; respiration ; Thiobencarb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of the herbicide thiobencarb (Saturn) were tested on the growth and physiology of the chlorophyte Protosiphon botryoides isolated from an Egyptian paddy. Assays were conducted using 16-day batch cultures. Chlorophyll and dry weight biomass yields were significantly reduced at 2–3 mg L-1 thiobencarb, and dark respiration increased and protein decreased significantly at 3 mg L-1. Reductions in exponential specific growth rate (μ) were generally small, but in some cases significant. Thiobencarb also slightly, but significantly, reduced the 77 K fluorescence parameter Fv/Fm, an indicator of maximum photosynthetic efficiency. No consistent dose-dependent changes occurred in chlorophyll per unit dry weight, total carbohydrate or gross photosynthetic capacity. Whereas half of the added thiobencarb was recovered from control (uninoculated) medium, it was largely absent from cells and culture medium after sixteen days, indicating biodegradation by the alga or associated bacteria. P. botryoides recovered fully within sixteen days following subculture in thiobencarb-free medium. Independently varying phosphate and nitrate nine-fold had no clear effect on the sensitivity of P. botryoides to thiobencarb.
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  • 90
    ISSN: 1573-5176
    Keywords: Cyanobacterium ; Spirulina platensis ; Arthrospira ; CO2 ; organic carbon ; nitrogen ; photosynthesis ; batch culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The consequences of the addition of CO2 (1%) in cultures of S. platensis are examined in terms of biomass yield, cell composition and external medium composition. CO2 enrichment was tested under nitrogen saturating and nitrogen limiting conditions. Increasing CO2 levels did not cause any change in maximum growth rate while it decreased maximum biomass yield. Protein and pigments were decreased and carbohydrate increased by high CO2, but the capability to store carbohydrates was saturated. C:N ratio remained unchanged while organic carbon released to the external medium was enhanced, suggesting that organic carbon release in S. platensis is an efficient mechanism for the maintenance of the metabolic integrity, balancing the cell C:N ratio in response to environmental CO2 changes. CO2 affected the pigment content: Phycocyanin, chlorophyll and carotenoids were reduced in around 50%, but the photosynthetic parameters were slightly changed. We propose that in S. platensis CO2 could act promoting degradation of pigments synthetised in excess in normal CO2 conditions, that are not necessary for light harvesting. Nitrogen assimilation was significantly not affected by CO2, and it is proposed that the inability to stimulate N assimilation by CO2 enrichment determined the lack of response in maximum growth rate.
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  • 91
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    Journal of applied phycology 11 (1999), S. 195-201 
    ISSN: 1573-5176
    Keywords: dense algal suspension ; light-harvesting pigment ; photosynthesis ; productivity ; cyanobacterium ; Synechocystis PCC 6714
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microalgal productivity was examined using both a wild type and a phycocyanin-deficient mutant of Synechocystis PCC 6714 (PD-1). The culture was conducted at various light intensities under low and high cell densities in a continuous culture system. At low light intensity, photosynthetic productivity was almost the same for both low and high cell densities. However, at higher light intensities photosynthetic productivity was higher in mutant PD-1 than in the wild type. At 2000 μmol photon m−2 s−1 the productivity was 50% higher in mutant PD-1. This result is consistent with our first report (Nakajima & Ueda, 1997), which showed that photosynthetic productivity can be improved by reducing the light harvesting pigment content in high cell density cultures at high light intensities. It is concluded that the technology for reducing LHP content is a useful method for improving photosynthetic productivity in algal mass production.
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  • 92
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    Journal of applied phycology 8 (1996), S. 263-273 
    ISSN: 1573-5176
    Keywords: molecular biology ; mutagenesis ; photosynthesis ; protein engineering ; respiration ; thylakoid membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cyanobacteriumSynechocystis sp. PCC 6803 is readily amenable to targeted mutagenesis: Foreign DNA is taken up spontaneously, and after uptake DNA can be integrated into the organism's genome by homologous recombination. Using appropriate DNA constructs for transformation, specific genes in the organism can be interrupted, deleted, or replaced by modified gene copies. The organism can grow under a number of different conditions, ranging from photoautotrophic to fully heterotrophic modes, making genetic modifications that alter fundamental processes such as photosynthesis and/or respiration feasible. For example, deletion of photosystem I leads to an obligate (photo)heterotrophic strain in which photosystem II-generated electrons appear to be consumed by respiratory processes, whereas deletion of photosystem II leads to an obligate (photo)heterotrophic strain in which cyclic electron flow around photosystem I appears to remain active. A major advantage ofSynechocystis sp. PCC 6803 is that its entire genome has been sequenced (by S. Tabata and co-workers), opening many avenues to address basic and applied research problems. For example, genes can be introduced, modified or deleted, and hypotheses regarding the function of an open reading frame can be tested by deletion of this open reading frame. Methods to modify genes are numerous. In addition to site-directed mutagenesis, novel molecular genetic approaches including ‘targeted random mutagenesis’, combinatorial mutagenesis and introduction of hybrid genes have come of age and have proven to be very powerful tools in protein engineering. These approaches have been utilized primarily in this strain to study photosynthesis, but applications of this technology, including pathway engineering, alterations of substrate specificity of enzymes and introduction of tolerance to a variety of stresses, are equally feasible in relation to more applied aims. For optimal utilization of the potential of theSynechocystis sp. PCC 6803 system, however, an increased emphasis toward understanding the biochemistry and molecular physiology of cyanobacteria will also be critically important.
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  • 93
    ISSN: 1573-5176
    Keywords: fluorescence ; photoinhibition ; photosynthesis ; Spirulina ; photobioreactor ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A chlorophyll fluorescence technique was applied to anin situ study on the effects of low temperature and high light stresses onSpirulina cultures grown outdoors in controlled tubular photobioreactors at high (1.1 g L−1) and low (0.44 g L−1) biomass concentrations. Diurnal changes in PSII photochemistry (F v/F m) after 15 min of darkness, or in the light (dF/F′ m), and non-photochemical (qN) quenching were measured using a portable, pulse-amplitude-modulated fluorometer. The depression of theF v/F m ratio ofSpirulina cultures grown outdoors at 25°C (i.e. 10°C below optimum for growth) and 0.44 g L−1, reached 30% at the middle of the day. At the same time of the day thedF/F′ m ratio showed a reduction of up to 52%. The depression of bothF v/F m anddF/F′ m was lower in the cultures grown at 1.1 g L−1. Photoinhibition reduced the daily productivity of the culture grown at 0.44 g L−1 and 25°C by 33% with respect to that grown at 35°C. Changes in the growth yields of the cultures grown under different temperatures and growth rates correlate well with analogous changes in photon yield (dF/F′ m). Simple measurements of photochemical yield (F v/F m) can be used to test the physiological status ofSpirulina cultures. The results indicate that the saturating pulse fluorescence technique, when usedin situ, is a powerful tool for assessment of the photosynthetic characteristics of outdoor cultures ofSpirulina.
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  • 94
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    Journal of applied phycology 10 (1998), S. 419-425 
    ISSN: 1573-5176
    Keywords: Gracilaria cornea ; photosynthesis ; respiration ; chlorophyll ; phycoerythrin ; Florida ; salinity ; temperature ; irradiance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The agarophyte Gracilaria cornea, collected over 2.5 y in the Florida Keys, shows adaptations to oceanic salinities and subtropical to tropical water temperatures in its photosynthetic and respiratory responses as measured with a respirometer. No seasonal pattern in responses to irradiance, temperature, and salinity were evident between five collections over a 20-month period, indicating the tropical nature of the populations from Bahia Honda and Pigeon Keys. Concentrations of chlorophyll a (0.09 to 0.41 mg g d wt-1) and phycoerythrin (0.06 to 0.36 mg g d wt- 1) were low and reflect the low nutrient regime of the habitats, especially when compared to laboratory cultured plants. Compensation and saturation irradiances were also low (11–38 and 90–127 μmol photon m-2 s-1), indicating acclimation to lower irradiances in their shallow (1–2 m depth) habitats where turbidity can be high. In comparison with other subtropical and warm temperate species of Gracilaria, G. cornea had lower levels of pigment, but similarly high photosynthetic efficiency, demonstrating shade adaptation; it had only limited tolerance to salinities below 20‰ and temperatures below 15 °C. Thus, G. cornea from the Florida Keys in mariculture would require subtropical to tropical temperatures and stable oceanic salinities.
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  • 95
    ISSN: 1573-5176
    Keywords: Chlorophyll antenna size ; damage and repair cycle ; photon use efficiency ; photosynthesis ; photoinhibition ; Dunaliella salina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The photon use efficiencies and maximal rates of photosynthesis in Dunaliella salina (Chlorophyta) cultures acclimated to different light intensities were investigated. Batch cultures were grown to the mid-exponential phase under continuous low-light (LL: 100 μmol photon m-2 s-1) or high-light (HL: 2000 μmol photon m-2 s-1) conditions. Under LL, cells were normally pigmented (deep green) containing ∼500 chlorophyll (Chl) molecules per photosystem II (PSII) unit and ∼250 Chl molecules per photosystem I (PSI). HL-grown cells were yellow-green, contained only 60 Chl per PSII and 100 Chl per PSI and showed signs of chronic photoinhibition, i.e., accumulation of photodamaged PSII reaction centers in the chloroplast thylakoids. In LL-grown cells, photosynthesis saturated at ∼200 μmol photon m-2 s-1 with a rate (Pmax) of ∼100 mmol O2 (mol Chl)-1 s-1. In HL-grown cells, photosynthesis saturated at much higher light intensities, i.e. ∼2500 μmol photon m-2 s-1, and exhibited a three-fold higher Pmax (∼300 mmol O2 (mol Chl)-1 s-1) than the normally pigmented LL-grown cells. Recovery of the HL-grown cells from photoinhibition, occurring prior to a light-harvesting Chl antenna size increase, enhanced Pmax to ∼675 mmol O2 (mol Chl)-1 s-1. Extrapolation of these results to outdoor mass culture conditions suggested that algal strains with small Chl antenna size could exhibit 2–3 times higher productivities than currently achieved with normally pigmented cells.
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  • 96
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    Journal of applied phycology 11 (1999), S. 157-163 
    ISSN: 1573-5176
    Keywords: Euglena gracilis ; photosynthesis ; waste water ; pulp and paper industry ; ultraviolet-B radiation (280–320 nm) ; pentachlorophenol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The green flagellate Euglena gracilis has been used as a model organism to elucidate the possible large-scale and short-term effects of waste substances from the pulp and paper industry on photosynthetic efficiency (PE). Different concentrations of waste substances before and after treatment in a cleaning system were studied. The uncleaned sample at concentrations up to 1:10 and the cleaned sample at concentrations up to 1:5 showed stimulating effects on the PE after 7 days of incubation compared to the control. The effects of waste substances on the PE of E. gracilis were also studied in combination with short-term studies (20 and 40 min) of ultraviolet-B radiation (UV-B, 280–320 nm). It was shown that increasing concentrations of the uncleaned sample had continuously stimulating effects on the PE and worked protectively against UV-B radiation. The cleaned sample exhibited no effects, or negative effects, on the PE of E. gracilis together with UV-B radiation compared to the experiments with only UV-B radiation. At the concentration 1:1 of the cleaned sample an increase in the PE was detected due to the high concentration of the coloured substances and a decrease in the UV-B penetration. PE revealed itself to be highly sensitive for detecting toxic effects on E. gracilis and is thus very promising for use in regular toxicity tests of waste water from pulp and paper industry.
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  • 97
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    Journal of applied phycology 10 (1998), S. 51-53 
    ISSN: 1573-5176
    Keywords: blue-green alga ; cyanobacterium ; Fv/Fmlight ; Nostoc flagelliforme ; photosynthesis ; rewetting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract PS II photochemical efficiency (Fv/Fm) of Nostoc flagelliforme was examined after rewetting in order to investigate the light-dependency of its photosynthetic recovery. Fv/Fm was not detected in the dark, but was immediately recognized in the light. Different levels of light irradiation (4, 40 and 400 µmol photon m2 s-1) displayed different effects on the recovery process of photosynthesis. The intermediate level led to the best recovery of photochemical efficiency; the low light required longer and the high light inhibited the extent of the recovered efficiency. It was concluded that the photosynthetic recovery of N. flagelliforme is both light-dependent and influenced by photon flux density.
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  • 98
    ISSN: 1573-5176
    Keywords: ammonium ; C:N ratio ; tank culture ; dietary fibre ; fatty acids ; nitrogen ; photosynthesis ; Ulva rigida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Physiological and biochemical changes in relation to inorganic nitrogen availability were studied for tank-cultivated Ulva rigida grown under nitrogen- enriched and nitrogen-depleted seawater. U. rigida was initially cultivated in nitrogen-enriched seawater (daily concentrations of NH4+ and NO3- + NO2- ranged between 0.5–1.7 and 0.06–0.15 mg L-1, respectively), then transferred to nitrogen-depleted seawater where photosynthetic capacity decreased to zero after 23 d. At the time (14 d) when photosynthetic rates were lower than 2.0 μmol O2 g-1 FW min-1 and strong bleaching had occurred, some algae were returned to the initial nitrogen-enriched seawater to study recovery from N-limited growth. Data on biochemical composition (chlorophylls, ash, caloric content, fatty acids and dietary fibres) and colouration varied significantly depending on the nitrogen conditions. C:N ratios correlated significantly with biochemical parameters. Fatty acid (FA) synthesis continued during the N-starvation period; saturated and mono-unsaturated FA increased to a maximun of 72.2%, while poly-unsaturated fatty acids (PUFA) decreased to 27.7%. During the N-enriched recovery period, the reverse was found. C:N ratios above 10 correlated with carbohydrate synthesis as shown by the dietary fibre level. Under nitrogen enriched conditions, C:N ratios decreased along with a decrease in fibre level. Under controlled conditions, nitrogen represents a major influence on the development of intensive tank cultivation of Ulva rigida, not only by affecting parameters closely related to nitrogen metabolism but also some clearly influenced by carbon uptake.
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  • 99
    ISSN: 1573-5176
    Keywords: herbicide ; DCMU ; photosynthesis ; monoalgal culture ; Chaetoceros ; Dunaliella ; Nannochloropsis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The selective effect of DCMU on photosynthetic activity and growth rate was examined in several marine unicellular algae:Nannochloropsis sp. (Eustigmatohyceae),Dunaliella salina (Chlorophyceae)Isochrysis galbana (Prymnesiophyceae) andChaetoceros sp. (Bacillariophyceae). DCMU at 10−7 M caused an immediate decrease in the photosynthetic rate ofDunaliella andIsochrysis (about 50% inhibition), whereas 10−6 M imposed 80% inhibition in the photosynthetic rate ofChaetoceros. InNannochloropsis the rate was affected only when DCMU concentration exceeded 10−6M. Cellular growth rate of all studied algae was affected by DCMU in a similar manner to photosynthesis. The differential effect of DCMU was further examined in mixed cultures in whichNannochloropsis was cultivated together with an additional species simulating a contamination situation of aNannochloropsis culture. When DCMU was added at concentrations higher than 10−7 M, the growth of the competing algae significantly decreased, whileNannochloropsis maintained a relatively high growth rate. Consequently, after a growth period of 4 to 7 days a clear domination ofNannochloropsis was observed. These results demonstrate that DCMU and probably other herbicides of similar characteristics can be used effectively as a selective tool to suppress contaminating unicellular algae in open ponds in order to maintain a monoculture ofNannochloropsis.
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  • 100
    ISSN: 1573-5176
    Keywords: Spirulina platensis ; cyanobacterium ; NaCl ; photoinhibition ; photosynthesis ; photosystem II ; salt stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The response ofSpirulina platensis cells to salinity stress was studied. Once adapted to the higher osmoticum, photosynthetic parameters such as the maximum rate of photosynthesis under saturating irradiance (Pmax) and the initial slope of the P-I curve (α) are reduced by 15% and 25% in 0.5 M NaCl grown cells, respectively. Salt-adapted cells have a modified biochemical composition; reduced protein and chlorophyll content, and an increased level of carbohydrates. The reduction in the photosynthetic capacity of the salt-adaptedSpirulina cells reflects a lower ability to utilize light energy and results in an increase in the susceptibility of the stressed cells to photoinhibition. This conclusion is supported by the finding that cultures exposed to salt stress show not only a decrease in growth rate (μ), but lose the ability to respond to increased irradiance with an increase in growth. The use of variable fluorescence as a fast and reliable measurement to follow the changes in PSII of salt-stressesSpirulina cells enables following the early events of salinity shock. It indicates that as soon as the cells are exposed to salt, a protection mechanism is induced. This mechanism does not require any protein synthesis and may take place even in the dark, though at somewhat reduced effectiveness. The significance of the result in providing a better understanding of the interaction between two environmental stresses — light and salinity — and their application in the outdoor mass cultivation ofSpirulina are discussed.
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