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  • Articles  (408)
  • wheat  (245)
  • Triticum aestivum  (229)
  • Springer  (408)
  • Oxford University Press
  • 2020-2023
  • 1995-1999  (408)
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  • Articles  (408)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 91 (1999), S. 403-412 
    ISSN: 1570-7458
    Keywords: aphid ; Diuraphis noxia ; Triticum aestivum ; endosymbiont ; insect-plant interactions ; phloem ; amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The feeding behavior of Diuraphis noxia Mordvilko (Homoptera: Aphididae) on susceptible hosts causes both ultrastructural and tissue level damage which may affect phloem composition. Genetic evidence suggests that endosymbiotic bacteria in most aphids overproduce limiting amino acids to benefit hosts but that D. noxia depends less on endosymbionts for these nutrients, possibly due to an enriched diet. To determine whether D. noxia feeding damage results in higher concentrations of essential amino acids, stylet exudates were analyzed from wheat (Triticum aestivum) damaged to different degrees. Comparison of samples from undamaged and damaged susceptible wheat revealed changes in amino acid composition and an increase in levels of essential amino acids, indicating a nutritionally enhanced ingesta. The changes in stylet exudates paralleled changes in leaf exudates, indicating that the effects are systemic. Feeding damage is not observed on a resistant wheat host, var. Halt, and leaf exudates from infested Halt did not show changes in amino acid composition. Mean relative growth of nymphs was significantly lower on Halt than on susceptible Arapahoe, indicating that Halt is a less suitable host. Both varieties show similar amino acid levels in non-infested samples, suggesting that D. noxia infestation does not enhance the phloem environment in Halt. This study provides evidence that aphid feeding can generate a nutritionally enhanced phloem diet.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 74 (1995), S. 115-119 
    ISSN: 1570-7458
    Keywords: wheat ; aphids ; hydroxamic acids ; DIMBOA ; DIMBOA-glucoside ; EPG ; electrical penetration graph ; feeding deterrents ; antixenosis ; plant resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Feeding behaviour of five species of cereal aphids in wheat seedlings differing in hydroxamic acid (Hx) levels, was monitored via electrical penetration graphs (EPG). Aphid species could be grouped as sensitive to the feeding deterrent effect of Hx in the seedlings (Rhopalosiphum padi, Schizaphis graminum, Sitobion avenae, andMetopolophium dirhodum) or insensitive to them (Rhopalosiphum maidis). However, when feeding behaviour was studied in artificial diets containing Hx, all species were equally sensitive to Hx. The behavour ofR. maidis was further compared with that ofR. padi through detailed EPG analysis. It was found that the insensitivity ofR. maidis to Hx in seedlings may be due to a feeding strategy avoiding contact with the compounds by decreasing the number of cellular punctures in live tissues other than sieve elements during its way to the phloem.
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  • 3
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    Entomologia experimentalis et applicata 74 (1995), S. 283-294 
    ISSN: 1570-7458
    Keywords: hypersensitivity ; Hessian fly ; plant resistance ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hessian flyMayetiola destructor (Say) larvae are able to obtain food from their host plant without inflicting mechanical damage to the plant surface, apparently by secreting substances which elicit release of nutrients from plant cells surrounding the feeding site. Cells of fully susceptible plants retain their normal appearances, while in resistant plants extensive areas of cellular collapse occur. These responses indicate that hypersensitivity is the basis of wheat's resistance to the Hessian fly. The fly's feeding mechanism more closely resembles that of a pathogen than of a phytophagous insect; correspondingly, both the genetic relationship and resistance mechanism of the host plant to the parasite are of the sorts commonly associated with bacterial and fungal pathogens.
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  • 4
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    Entomologia experimentalis et applicata 93 (1999), S. 227-230 
    ISSN: 1570-7458
    Keywords: Rhopalosiphum padi ; cereal aphids ; wheat ; induced responses ; feeding site
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 5
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    Entomologia experimentalis et applicata 92 (1999), S. 157-164 
    ISSN: 1570-7458
    Keywords: plant resistance ; antibiosis ; tolerance ; antixenosis ; Russian wheat aphid ; wheat ; Homoptera ; Aphididae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Russian wheat aphid, Diuraphis noxia (Mordvilko), is one of the most important aphid pests of wheat, Triticum aestivum L., worldwide. Among the various pest management options, plant resistance is an economical management tactic to control D. noxia in cereal crops such as wheat. Researchers have identified D. noxia resistant germplasm and it has been incorporated into wheat. This study compared D. noxia resistance between the ‘Betta’ wheat isolines Betta-Dn1, Betta-Dn2, and Betta-Dn5 and their corresponding donor gene plant introduction (PI) lines PI 137739 (Dn1), PI 262660 (Dn2), and PI 294994 (Dn5). Although the Betta isolines and PI lines showed D. noxia resistance when compared with Betta wheat, the degree of resistance in the isolines to D. noxia was different from their corresponding PI donors. Aphid number, aphid fecundity, and biomass per aphid were not different between Betta-Dn1 and PI 137739 or Betta-Dn2 and PI 262660; however, the same parameters were significantly lower on PI 294994 compared with Betta-Dn5. This indicated that aphid resistance in PI 137739 and PI 262660 was probably governed by a single dominant gene, while the resistance in PI 294994 was controlled by more than one gene. Additionally, plant biomass reduction was aphid density dependent, which suggested that use of appropriate aphid infestation level is important when using plant biomass reduction as an indicator of resistance. Plant resistance categorization showed that there was no detectable difference in antixenosis among the seven lines evaluated. However, the higher aphid fecundity observed on PI 262660 compared with PI 137739 and PI 294994, in addition to no significant differences among the three PIs in plant biomass reduction, suggested PI 262660 was a tolerant line, while PI 137739 and PI 294994 were antibiotic lines. Plant tolerance could not be elucidated among the three Betta isolines using aphid fecundity and plant biomass reduction as indicators.
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  • 6
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    Entomologia experimentalis et applicata 89 (1998), S. 111-118 
    ISSN: 1570-7458
    Keywords: leaf surface wax ; probing behavior ; nymphoposition ; Russian wheat aphid ; wheat ; barley ; oat ; Homoptera ; Aphididae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of cereal leaf surface wax on Diuraphis noxia (Mordvilko), the Russian wheat aphid, probing behavior and nymphoposition was evaluated. Ultrastructure of leaf epicuticular wax from wheat (Triticum aestivum L.) c.v. ‘Arapahoe’ and ‘Halt’ was different from barley (Hordeum vulgare L.) c.v. ‘Morex’, and oat (Avena sativa L.) c.v. ‘Border’. Both wheat cultivars had similar rod-shaped epicuticular wax, while barley and oat plants had flakes. The chemical composition comparison of gas chromatograms also indicated that the extract of the two wheat cultivars had similar pattern of peaks, while the barley and oat leaves had similar peaks. Cereal variety significantly affected aphid probing behavior (P 〈 0.05), but wax removal using ethyl ether swab did not (P 〈 0.05). Aphids initiated significantly more probes on Border oat leaves than on Morex barley irrespective of wax removal, although total probing duration per aphid was not significantly different among the four cereals examined. Accumulative salivation duration per aphid on oat leaves with wax was significantly longer than other cereal leaves with wax, while accumulative ingestion duration per aphid on Arapahoe wheat and Morex barley was significantly longer than on oat. Nymphoposition of D. noxia on cereal leaves maintained on the benzimidazole-agar medium showed that aphids produced a greater number of nymphs on Morex barley and less on Border oat leaves, although wax removal did not affect aphid nymphoposition. Removal of leaf epicuticular waxes from the 4 cereal genotypes using ethyl ether swab indicated that the influence of wax on plant resistance to D. noxia probing and reproduction was limited. Morex barley was the most favorable, while Border oat was the least favorable cereal host of D. noxia.
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  • 7
    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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  • 8
    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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  • 9
    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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  • 10
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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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  • 11
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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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  • 12
    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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  • 13
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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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  • 14
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    Plant molecular biology reporter 17 (1999), S. 323-331 
    ISSN: 1572-9818
    Keywords: Agrobacterium ; modular vector ; transformation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wheat (cv Chinese Spring) tissues were transformed using Agrobacterium tumefasciens and a new plasmid modular vector, pMVTBP. We constructed pMVTBP with unique restriction sites connecting (1) the CaMV 35S promoter, (2) a Kozak sequence, (3) the FLAG epitope, (4) the (His)6 epitope, (5) a coding region (for wheat TATA Binding Protein, wTBP) and (6) the CaMV 35S 3′UTR. This vector thus allows easy exchange of different regulatory or coding sequences. Explants of either germinating mature seeds, or immature embryos, were induced to callus for up to two weeks, treated with virulence-induced bacteria for one hour, then regenerated into plantlets. Transient expression of a GUS reporter gene, assayed at about one week, occurred in 10–12% of calluses. Expression of the FLAG-tagged wTBP was also detected, by immunostaining. Stable expression, by selective growth on geneticin, and by GUS expression at about six weeks, occurred in 1–2% of calluses, quite comparable to that achieved by other methods.
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  • 15
    ISSN: 1573-0832
    Keywords: deoxynivalenol ; enzyme immunoassay ; feed ; maize ; mycotoxins ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Samples of wheat (n = 25) and maize (n = 30) for animal consumption, collected in 1997 after harvest from western Romania, were analyzed by enzyme immunoassays for mycotoxin contamination. Toxins analyses included deoxynivalenol (DON), 3-acetylDON, 15- acetylDON, fusarenone X (FX), T-2 Toxin (T-2), diacetoxyscirpenol (DAS), zearalenone (ZEA), fumonisin B1 (FB1), aflatoxin B1 (AFB1), ochratoxin A (OA), and citrinin (CT). DON and acetylDONs were the major contaminants in wheat (100%) and maize (46%). Median values for DON, 3-acetylDON, and 15-acetylDON were 880 μg kg-1, 66 μg kg- 1, and 150 μg kg-1 in wheat, and 890 μg kg-1, 180 μg kg-1, and 620 μg kg- 1 in maize, respectively. Additionally, 3,15-diacetylDON was detected in some samples by HPLC-EIA analysis. All samples were negative for FX (〈150 μg kg-1). T-2 was found in wheat (n = 6) and maize (n = 1) at levels between 13 and 63 μg kg- 1. DAS (2.6 μg kg-1) was found in one maize sample. ZEA occurred in all wheat and in four maize samples, median values were 10 μg kg-1 and 250 μg kg-1, respectively. One maize sample contained FB1 (140 μg kg-1). All samples were AFB1-negative (〈4 μg kg-1). OA was found in one wheat sample (37 μg kg- 1), CT was found in one maize sample (580 μg kg- 1). This first reported natural occurrence of a range of mycotoxins in Romanian feeding stuff shows that DON and acetyl DONs may be present at levels which may affect animal production.
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  • 16
    ISSN: 1573-0832
    Keywords: Fusarium ; mycotoxins ; occurrence ; trichothecenes ; wheat ; zearalenone ; deoxynivalenol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Wheat for human consumption (140 samples) was collected after harvest from all regions of Bulgaria. The 1995 crop year was characterized by heavy rainfall in the spring and summer months. The internal mycoflora of wheat samples was dominated by Fusarium spp. and Alternaria spp., and storage fungi were rarely present. The samples were analysed for contamination with Fusarium mycotoxins deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-AcDON), 15-acetyldeoxynivalenol (15-AcDON), T-2 Toxin (T-2), diacetoxyscirpenol (DAS), and zearalenone (ZEA), using enzyme immunoassay methods. DON and ZEA were the predominant toxins, with a contamination frequency of 67% and 69%, respectively. The average levels of these toxins in positive samples were 180 μg/kg (DON) and 17 μg/kg (ZEA), maximum concentrations were 1800 μg kg−1 and 120 μg kg−1, respectively. Acetyl derivatives of DON, namely 3-AcDON and 15-AcDON, were found in 2.1 % and 0.7% of the samples, at at maximum level of about 100 μg kg−1. Only one sample was positive for T-2 (55 μg/kg), DAS was not detected. This is the first report about the natural occurrence of a range of Fusarium mycotoxins in wheat for human consumption in Bulgaria.
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  • 17
    ISSN: 1573-0867
    Keywords: 15N ; non-nod beans ; quantification of N2 fixation ; reference crops ; simulation technique ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A technique for the application of the15N isotope dilution technique for the quantification of plant associated biological nitrogen fixation (BNF) was tested and applied to quantify the BNF contribution to two genotypes ofPhaseolus vulgaris. The technique makes use of sequential measurements of the15N enrichment of soil mineral N, and the uptake of labelled N by the “N2-fixing” plant, to simulate its uptake of soil N (the “soil to plant simulation” technique). The test was made with two non-N2-fixing crops (non-nodulating beans and wheat) and two bean genotypes (PR 923450 and Puebla 152), at two levels of N fertilizer addition (10 and 40 kg N ha−1), to compare the actual N uptake with that simulated from the soil and crop15N data. The simulation of the soil N uptake by the non-nod bean crop using this “soil to plant simulation” technique underestimated by 20 to 30% the true N uptake, suggesting that the mineral N extracted from soil samples taken from the 0–15cm layer had a higher15N enrichment than that N sampled by the roots of this crop. In the case of the wheat crop the simulation resulted in a much greater underestimation of actual N uptake. In general the results using this technique suggested that BNF inputs to the bean cultivars was higher than would be expected from the nodulation and acetylene reduction data, except for the early PR beans in the 40 kg N ha−1 treatment. In this case the total N and simulated soil N accumulation were well matched suggesting no BNF inputs. An allied technique (the “plant to plant simulation technique”) was proposed where the15N enrichrnent of soil mineral N was simulated from the data for total N and labelled N accumulation taken from sequential harvests of either of the non-N2 -fixing control crops. This was then utilized in combination with the labelled N uptake data of the other crop to simulate its soil N uptake. However, the results using either technique indicated that the wheat and non-nod or nodulating beans exploited pools of N in the soil with completely different15N enrichments probably due to differences in exploitation of the soil N with depth.
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  • 18
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    Nutrient cycling in agroecosystems 45 (1995), S. 209-215 
    ISSN: 1573-0867
    Keywords: climate ; fertilizer recovery ; 15N fertilizer ; precipitation-evaporation quotient ; soil ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Data was assembled from experiments on the fate of15N-labelled fertilizer applied to wheat (Triticum spp.) grown in different parts of the world. These data were then ranked according to the annual precipitation-evaporation quotient for each experimental location calculated from the average long-term values of precipitation and potential evaporation. Percentage recovery of15N fertilizer in crop and soil varied with location in accordance with the precipitation-evaporation quotient. In humid environments more15N fertilizer was recovered in the crop than in the soil, while in dry environments more15N fertilizer was recovered in the soil than in the crop. Irrespective of climatic differences between locations 20% (on average) of the15N fertilizer applied to wheat crops was unaccounted for at harvest. Most of the15N fertilizer remaining in the soil was found in the 0–30 cm layer. The most likely explanation of these differences is that wheat grown in dry environments has a greater root:shoot ratio than wheat grown in humid environments and, further, that the residue of dryland crops have higher C/N ratios. Both factors could contribute to the greater recovery of15N fertilizer in the soil in dry environments than in humid ones.
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  • 19
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    Nutrient cycling in agroecosystems 46 (1996), S. 225-234 
    ISSN: 1573-0867
    Keywords: long-term experiment ; maize ; wheat ; fertilizers ; farm yard manure ; weedicide application ; yield sustainability ; zinc deficiency ; nutrient uptake ; cropping sequence ; organic carbon build-up
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Long-term field experiments play an important role in understanding the complex interactions of plants, soils, climate and management and their effects on sustainable crop production. A long-term fertilizer experiment with maize-wheat-cowpea (fodder) is in progress since 1971 at Punjab Agricultural University farm Ludhiana, India. The experimental result for the first 21 years showed that application of N alone or in combination with P did not produce as much maize and wheat grains as the application of N, P and K together. Eight years after the start of the experiment, the optimal levels of N, P and K application (100% NPK) were unable to sustain the similar (maize) yield level as before because of Zn deficiency. Whereas in FYM amended plots the Zn deficiency did not appear and the higher crop yields could be sustained. The chemical control of weeds could not sustain the maize productivity at the same level as the manual removal of weeds. It was concluded that the high level of crop production can be sustained with the application of N, P and K under intensive cropping system provided deficiency of any of the micronutrient does not crop up. The deficiency of Zn is most likely to occur in semi-arid light textured alluvial soils under intensive cropping without the addition of farm yard manure/organic manures. In maize based cropping systems, manual control of weeds may be preferred to the chemical one. Addition of FYM in conjunction with 100% NPK is most beneficial both from bio-physical and economic point of view.
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  • 20
    ISSN: 1573-0867
    Keywords: millet ; sorghum ; rice ; maize ; wheat ; nutrient harvest index ; post-anthesis nutrient uptake ; recovery fraction ; simulation modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In land use plans, fertilizer recommendations are indispensable to avoid soil nutrient depletion or soil water pollution. Nutrient relations of five cereals have been evaluated on the basis of a literature review with the aim of arriving at such fertilizer recommendations at regional level. Nutrients considered were nitrogen, phosphorus and potassium for millet, sorghum, maize, rice and wheat. The relevant nutrient relations are fertilizer nutrient application to nutrient uptake, and nutrient uptake to crop yield. In addition, post-anthesis nutrient uptake is considered. Subsequently, obtained results are used in simulation modelling exercises to calculate the time required to attain an equilibrium nutrient balance and to investigate the effect of erosion control and straw recycling. Although fertilizer requirements could be assessed for each of the five cereals, monitoring of nutrient supply from natural sources remains necessary. Moreover, research on fertilizer use should focus on improvement of fertilizer recoveries and multiperiod models for both N and P uptakes by crops to allow quantitative land use planning where the time scale is included.
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    Nutrient cycling in agroecosystems 44 (1995), S. 217-223 
    ISSN: 1573-0867
    Keywords: foliar fertilizer ; nitrate ; potassium ; urea ; wheat ; yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Winter wheat crops were grown with ostensibly adequate supplies of all soil nutrients in 1990 and 1991 with the aim of testing if late foliar supplements of K and N, applied at key development stages, could improve grain yield and grain N content. Foliar sprays of KNO3 solution, supplying up to 40 kg K ha−1 in total, at flag leaf unfolded, inflorescence completed and the watery-ripe stage of grain filling, had no effect on yield, yield components or grain N. Urea, supplying 40 kg N ha−1 at flag leaf unfolded, had no effects on grain yield and grain N in 1990, but in 1991 grain N was increased by 0.14% whilst yield was reduced by up to 0.6 t ha−1. Urea scorched flag leaf tips in both years. In 1990, the spring was very dry and foliar supplements might have been expected to have had an effect, but on this highly fertile soil all crop K and N requirements were met from the soil.
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  • 22
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    Nutrient cycling in agroecosystems 53 (1999), S. 139-146 
    ISSN: 1573-0867
    Keywords: critical levels of Mn ; soil extractants ; Mn-deficiency ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seven chemical extractants were tested for their relative performance to predict the response of wheat to Mn application in coarse textured alkaline soils of semi-arid region. Five out of the seven extractants were found to be promising for the estimation of critical level of available Mn in these soils, as the amount of Mn extracted by these extractants was positively and significantly correlated with relative grain yield as well as Mn uptake. The critical deficiency level of soil available Mn with 0.005 M DTPA, 0.02% hydroquinone, 0.02 N sodium pyrophosphate, 0.1N H3PO4 and 0.05N HCl+0.025N H2SO4 was 3.1, 13.8, 23.5, 5.3 and 17.8 mg kg-1 soil, respectively. The 1N ammonium acetate and 0.01M CaCl2 were found to be unsuitable extractants for these soils. Further field trials at eight locations with varying levels of Mn deficiency showed successive increase in the grain yield of wheat with foliar Mn application, emphasizing the need for Mn fertilization when wheat is grown on Mn deficient soils.
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  • 23
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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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    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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    Nutrient cycling in agroecosystems 45 (1995), S. 163-167 
    ISSN: 1573-0867
    Keywords: Basal dressing ; Se-enriched fertilizers ; Se-uptake ; soil texture ; top-dressing ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A multisite field experiment was conducted to study the effect of topdressed Se-enriched Ca(NO3)2 (CN) and basal applied NPK on the selenium (Se) concentration in spring wheat (Triticum aestivum L.). Selenium was applied either through CN (at the rates of 0, 6.45, and 12.91 g Se ha−1) or NPK (5.83 g Se ha−1). Selenium concentration in wheat grains increased consistently with increasing rate of Se-enriched CN or NPK. However, the superiority of Se-enriched CN over NPK in raising the Se concentration in wheat grain depended on location and growth conditions. At the same rate both methods of Se-application were found to be equally effective in raising the Se concentration of wheat grains. The Se concentration of grain was generally higher in the light textured soils than in the medium to heavy textured soils. Without Se application, the Se-concentration in wheat grain was about 16µg kg−1 which is regarded insufficient to meet the Se requirement for Se in animal and human. Calcium nitrate enriched with 25 mg Se kg−1 (6.45 g Se ha−1) increased the Se concentration in wheat grain to a desired level.
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  • 26
    ISSN: 1572-9699
    Keywords: bioluminescence ; Pseudomonas ; root colonization ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The bioluminescently marked Pseudomonas fluorescens strain 5RL, has been used previously to follow colonisation of soy bean roots (De Weger et al. [1991] Appl. Environ. Microbiol. 57:36-41). In the present paper the method has been further developed and optimized for wheat roots and it is used to get a quick overview of the colonisation patterns of many different root systems at the same time. Colonisation was followed on wheat plants grown in our gnotobiotic sand system (Simons et al., 1996. Mol Plant Microbe Interact 9: 600–607) and the following results were obtained. (i) A spatio-temporal analysis of the colonisation of wheat roots showed that 4 days after planting the highest bacterial activity was observed at the upper part of the root. After 6 days the high bacterial activity at the upper part was further increased, whereas spot-like activities were observed on the lower root parts, possibly due to micro-colonies. (ii) Bacterial mutations causing lack of motility or auxotrophy for amino acids resulted in impaired colonisation of the lower root parts, indicating that motility and prototrophy for the involved amino acid(s) are important factors for wheat root colonisation by strain 5RL. (iii) Coinoculation of strain 5RL with other wild type Pseudomonas strains on the root influenced the colonisation pattern observed for strain 5RL. Colonisation was not visually affected when the competing strain was a poor root coloniser, but was severely reduced when the competing strain was a good root coloniser. The results show that the spatio-temporal colonisation of wheat root by P. fluorescens strain 5RL and derivatives is similar to that of strain WCS365 on tomato. The advantage of the use of lux-marked strains is that the results are obtained much quicker than when conventional methods are used and that the result is supplied as an image of the colonisation pattern of many different roots.
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  • 27
    ISSN: 1572-9761
    Keywords: Coccinellidae ; Aphididae ; wheat ; spatial scale ; species diversity ; numerical response
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    Topics: Biology
    Notes: Abstract The influence of prey density, within-field vegetation, and the composition and patchiness of the surrounding landscape on the abundance of insect predators of cereal aphids was studied in wheat fields in eastern South Dakota, USA. Cereal aphids, aphid predators, and within-field vegetation were sampled in 104 fields over a three year period (1988–1990). The composition and patchiness of the landscape surrounding each field were determined from high altitude aerial photographs. Five landscape variables, aggregated at three spatial scales ranging from 2.6 km2 to 581 km2, were measured from aerial photographs. Regression models incorporating within-field and landscape variables accounted for 27–49% of the variance in aphid predator abundance in wheat fields. Aphid predator species richness and species diversity were also related to within-field and landscape variables. Some predators were strongly influenced by variability in the composition and patchiness of the landscape surrounding a field at a particular spatial scale while others responded to variability at all scales. Overall, predator abundance, species richness, and species diversity increased with increasing vegetational diversity in wheat fields and with increasing amounts of non-cultivated lands and increasing patchiness in the surrounding landscape.
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    Integrated pest management reviews 4 (1999), S. 127-143 
    ISSN: 1572-9745
    Keywords: wheat ; stored-grain ; integrated pest management ; aeration ; biological control ; grain sampling ; insect monitoring ; modeling ; area-wide IPM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Management of stored-grain insect pests by farmers or elevator managers should be based upon a knowledge of the grain storage environment and the ecology of insect pests. Grain storage facilities and practices, geographical location, government policies, and marketing demands for grain quality are discussed as factors influencing stored-grain insect pest management decisions in the United States. Typical practices include a small number of grain samples designed to provide grain quality information for segregation, blending and marketing. This low sampling rate results in subjective evaluation and inconsistent penalties for insect-related quality factors. Information on the efficacy of insect pest management practices in the United States, mainly for farm-stored wheat, is discussed, and stored-grain integrated pest management (IPM) is compared to field-crop IPM. The transition from traditional stored-grain insect pest control to IPM will require greater emphasis on sampling to estimate insect densities, the development of sound economic thresholds and decision-making strategies, more selective use of pesticides, and greater use of nonchemical methods such as aeration. New developments in insect monitoring, predictive computer models, grain cooling by aeration, biological control, and fumigation are reviewed, their potential for improving insect pest management is discussed, and future research needs are examined.
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  • 29
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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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  • 30
    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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    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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  • 32
    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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  • 33
    ISSN: 1573-1561
    Keywords: Kairomone ; biological control ; cabbage ; wheat ; Diuraphis noxia ; Brevicoryne brassicae ; olfactometer ; infochemical ; preference ; host plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Diaeretiella rapae (M'Intosh) (Hymenoptera: Aphidiidae) is a parasitoid of several aphid species, including the Russian wheat aphid (RWA),Diuraphis noxia (Mordvilko), and the cabbage aphid (CA).Brevicoryne brassicae (L.). The response of matedD. rapae females to odors from wheat, cabbage, and plant-host complexes was investigated using a four-choice olfactometer. Experienced parasitoids, but not inexperienced females, responded positively to odors of the wheat-RWA complex in a no-choice test. In choice tests, experienced parasitoids did not respond to odors of uninfested cabbage and wheat leaves, but did respond positively to aphid-infested plants and to aphids alone. The response ofD. rapae to the cabbage-CA complex and to CA alone was significantly greater than to the wheat-RWA complex and RWA alone, suggesting an innate odor preference for crucifer-feeding aphids.
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  • 34
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    Journal of chemical ecology 23 (1997), S. 2695-2705 
    ISSN: 1573-1561
    Keywords: Defense ; herbivory ; aphids ; wheat ; Gramineae ; hydroxamic acids ; Defense theory ; Carbon/Nutrient theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Hydroxamic acids (Hx) are natural products of Gramineae that are associated with cereal resistance to pests. We aimed at characterizing the induction of Hx accumulation in seedlings of wheat,Triticum aestivum, by short-term infestation of the cereal aphid,Rhopalosiphum padi. A load of 25 aphids increased significantly the Hx levels in the infested primary leaf in comparison with control levels. Lower loads did not increase Hx concentration. Aphid infestation lasting 16 hr did not elicit induction of Hx, even after a time-lag of 32 hr to allow the expression of any induced response. Forty-eight hours was the minimum duration of aphid infestation required to trigger Hx induction. The age of the infested tissue (the primary leaf) did not affect induction. Similar increases of Hx were found in unfolding, expanding, and totally expanded primary leaves. It was determined that the regime of nutrient supply (N-intensive nutritive solutions at low and high concentration) to wheat seedlings had no effect on the magnitude of the aphid-induced Hx (N-based secondary metabolites). Results obtained are discussed in the framework of general theories of plant defense allocation.
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    Water, air & soil pollution 85 (1995), S. 1311-1316 
    ISSN: 1573-2932
    Keywords: Pakistan ; air pollution ; ozone ; nitrogen dioxide ; rice ; wheat ; filtration ; yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Open-top chambers ventilated with ambient or chiarcoal-filtered air were used to assess the impact of air pollution on the yield of local cultivars of wheat and rice, at a site on the outskirts of Lahore. At this location, 6-h mean O3 concentrations reach 60 ppb in certain months, and annual mean NO2 concentrations are 20–25 ppb. The experiments showed significant yield reduction in two successive seasons which ranged from 33% to 46% in wheat and from 37% to 51% in rice. The major yield parameter affected was the number of ears or panicles per plant, although there was also evidence of small effects on 1000 grain weight and on the number of grains per ear/panicle. These results have significance in terms of the maintenance of agricultural yields as pollution emissions rise in south and south-east Asia.
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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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  • 37
    ISSN: 1573-2932
    Keywords: Ozone ; wheat ; areal interpolation ; economics ; yield losses ; critical levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In Britain wheat is an important crop accounting for 41% of the total cereal production. In this study ozone concentrations for 1989 estimated as described in Part 1 of the paper are integrated with the estimated wheat distribution to derive a detailed estimate of the impact of ozone on wheat yields at a fine spatial scale (1km × 1km). These data provide estimates for calculating regional and national yield losses. The methodology can be applied to other crop species. Recent research on a range of crops has established relationships between the economic yield loss for certain crops, including wheat, and ozone exposure. Exposure is described as the accumulated exposure above a threshold experienced during the daylight hours (AOT). Critical AOT values are derived from yield exposure relationships which show linear reductions of yield loss with increasing ozone concentrations. This study has made use of land cover data from remotely sensed imagery at 25m resolution and nationally collected agricultural statistics for counties. These data were combined using an areal interpolation technique to provide more spatially articulate estimates of the location and intensity of wheat production. The results demonstrate the economic importance of ozone as a pollutant. Wheat yield losses attributed to ozone vary between different parts of the country but, for years when ozone levels are high, yield losses are likely to be significant in some areas.
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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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    Plant molecular biology 30 (1996), S. 1301-1306 
    ISSN: 1573-5028
    Keywords: abscisic acid ; glycine-rich ; ribonucleoprotein ; RNA-binding protein ; RNP motif ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A wheat cDNA encoding a glycine-rich RNA-binding protein, whGRP-1, was isolated. WhGRP-1 contains two conserved domains, the RNA-binding motif (RNP motif) combined with a series of glycine-rich imperfect repeats, characteristic of a conserved family of plant RNA-binding proteins. Northern analysis revealed that whGRP-1 mRNA accumulates to high levels in roots and to lower levels in leaves of wheat seedlings. whGRP-1 mRNA accumulation is not enhanced by exogenous abscisic acid in seedlings and accumulates to very high levels during wheat embryo development, showing a pattern different from that of the ABA-inducible wheat Em gene.
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  • 40
    ISSN: 1573-5028
    Keywords: differential display ; heat shock proteins ; non-coding regions ; PCR ; reverse transcription ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Isolation of cDNAs encoding individual members of a gene family is essential for assessing their role in a biological phenomenon. However, this process is often laborious and slow due to highly conserved protein-coding region that interferes with the isolation of the individual members. Identification of gene-specific probes from 3′ non-coding regions of different members can assist in the fast retrieval and characterization of individual members of a multigene family. We used the recent technique of differential display for the same purpose. As an example of a multigene family in plants, we selected a heat shock protein gene family, HSP16.9 from wheat, with estimated 12 members. We modified the original differential display technique for selective amplification of the 3′ non-coding regions of different wheat HSP16.9 genes by replacing the random 10-mer in the original method with a conserved HSP16.9 gene family-specific primer. Sixteen cDNA fragments from these experiments were sequenced and they represent 8 different members of a 12 member gene family. Our succes can be attributed to shorter 3′ non-coding regions that are typical of higher-plant genes and use of highly conserved gene family-specific primer in these experiments. This modified differential display technique can be of general application to other plant systems where cloning of the different members of a gene family is desired.
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  • 41
    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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  • 42
    ISSN: 1573-5028
    Keywords: male sterility ; ovary ; parthenogenetic lines ; pollen allergen ; subtractive hybridization ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To isolate genes specifically expressed at the initiation of plant embryo development we have applied a sensitive subtractive hybridization technique for three isogenic wheat lines of the so-called ‘Salmon system’ with either zygotic or autonomous embryo development. Here we present a gene sequence showing a high homology to grass pollen allergens of type II/III thought to be expressed in pollen tissue only. Surprisingly, the pollen allergen-like sequence, designated Tri a III, is also expressed in gynoecia of the sexual, male fertile wheat line ‘(aestivum)-Salmon’, whereas the two parthenogenetic and male sterile wheat lines ‘(caudata)-Salmon’ and ‘(kotschyi)-Salmon’ completely lack any Tri a III transcript. Our data suggest a positive correlation between the expression of this clone and the manifestation of male fertility. Northern and in situ hybridization analysis revealed that, in addition to its presence in pollen, Tri a III is expressed in the parenchymatous tissue of ‘(aestivum)-Salmon’ ovaries exclusively at the day of anthesis. This precise temporal and spatial expression pattern suggests a more general function of the pollen allergen-like sequence Tri a III not limited to the exhibition of allergens in pollen grains.
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  • 43
    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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  • 44
    ISSN: 1573-5028
    Keywords: ADP-glucose pyrophosphorylase ; anther ; pollen ; male sterility ; water stress ; wheat ; starch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In wheat (Triticum aestivum L.), water deficit during meiosis in the microspore mother cells (MMCs) induces pollen abortion, resulting in the failure of fertilization and a reduction in grain set. In stressed plants, meiosis in MMCs proceeds normally but subsequent pollen development is arrested. Unlike normal pollen grains, which accumulate starch during the late maturation phase, stress-affected anthers contain pollen grains with little or no starch. Stress also alters the normal distribution of starch in the anther wall and connective tissue. To determine how starch biosynthesis is regulated within the developing anthers of stressed plants, we studied the expression of ADP-glucose pyrophosphorylase (AGP), which catalyzes the rate limiting step of starch biosynthesis. Two partial-length cDNAs corresponding to the large subunit of AGP were amplified by RT-PCR from anther RNA, and used as probes to monitor AGP expression in developing anthers of normal and water-stressed plants. These clones, WAL1 and WAL2, had identical deduced amino acid sequences and shared 96% sequence identity at the nucleic acid level. In normal anthers, AGP expression was biphasic, indicating that AGP expression is required for starch biosynthesis both during meiosis and later during pollen maturation. AGP expression in stressed anthers was not affected during the first phase of starch accumulation, but was strongly inhibited during the second phase. We conclude from these results that the reduced starch deposition later in the development of stressed pollen could be the result of a lower expression of AGP. However, this inhibition of AGP expression is unlikely to be the primary cause of male sterility because anatomical symptoms of pollen abortion are observed prior to the time when AGP expression is inhibited.
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  • 45
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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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  • 46
    ISSN: 1573-5028
    Keywords: cDNAs ; expression ; mapping porin ; VDAC ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mitochondrial outer membrane of eukaryotic cells contains voltage-dependent anion channels (VDAC) also termed porins. Three cDNAs from wheat (Triticum aestivum) were isolated and sequenced (Tavdac 1–3). They share 65% similarity of their amino acid sequences, and therefore they probably represent isoforms. The deduced amino acid sequence of one of the cDNAs was found to be identical to the purified VDAC protein from wheat mitochondria [8]. Secondary structure analysis of the deduced amino acid sequences of the three vdac cDNAs revealed a characteristic α helix at their N-terminal and β-barrel cylinders characteristic of VDAC channels. The Tavdac cDNAs are differentially expressed in meristematic tissues. The transcript levels of Tavdac 1 in all wheat tissues is at least 2.5-fold higher than Tavdac 2 and Tavdac 3. Tavdac 2 has a low level of expression in all floral tissues whereas Tavdac 3 is highly expressed in anthers. This is the first report on differential expression of vdac genes in plants. The Tavdac genes have been mapped on the wheat genome. Tavdac 1 is located on the long arm of chromosome 5, Tavdac 2 on the long arm of chromosome 1 and Tavdac 3 on the long arm of chromosome 3. A phylogenetic reconstruction indicates that vdac genes underwent numerous duplication events throughout their evolution. All duplications occurred after the separation of plants from animals and fungi, and no orthologous genes are shared among phyla. Within plants, some of the vdac gene duplications probably occurred before the monocotydelon-dicotydelon split.
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  • 47
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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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  • 48
    ISSN: 1573-5028
    Keywords: cDNA ; expression ; FKBP ; PPIase ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A novel cDNA encoding for a peptidyl-prolyl-cis-trans-isomerase (PPIase) belonging to the FK506-binding protein (FKBP) family was isolated from wheat. It contains an open reading frame of 559 amino acids and it represents the first plant FKBP-PPIase to be cloned. It possesses a unique sequence which is composed of three FKPB-like domains, in addition to a putative tetratricopeptide repeat (TPR) motif and a calmodulin-binding site. The recombinant FKBP-PPIase expressed in and purified from Escherichia coli exhibits PPIase activity that is efficiently inhibited by the immunosuppressive drugs FK506 and rapamycin. Northern blot analysis showed that wheat FKBP was found mainly in young tissues. Polyclonal antibodies revealed the presence of cross-reacting proteins in embryos, roots and shoots. The unique structural features, the enzymatic activity and the presence of putative isoforms in wheat tissues indicate the possibility of the involvement of wheat PPIase in essential biological functions, similar to other members of the FKBP gene family.
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  • 49
    ISSN: 1573-5028
    Keywords: chloroplast ; in vitro transcription ; light ; psbA ; psbD/C operon ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dynamical aspects of three chloroplast promoters responding to change in light condition were examined in mature chloroplasts of wheat (Triticum aestivum) by in vitro transcription. The wheat psbD/C operon has four distinct promoters, two of which named as D/C-3 and D/C-4 promoters dominantly function in mature chloroplasts to produce the mRNAs encoding D2/CP43 and CP43 alone, respectively. Activity of the D/C-3 promoter in mature chloroplasts was reduced to less than 30% by 24 h dark adaptation and recovered by re-illumination to the original level within 30 to 60 min. The activation of the D/C-3 promoter which requires de novo cytoplasmic protein synthesis was induced by low fluence of light (e.g. 16 µE m-2 s-1), but the extent of activation increased with increasing light fluence. The accumulation of mRNAs from the D/C-3 promoter saturated at 2- to 3-fold higher level within 2 h when the dark-adapted seedlings were transferred to the lig at 72 µE m-2 s-1, concomitant with the increase in rate of D2 synthesis, suggesting that synthesis of D2 in mature chloroplasts is controlled via the D/C-3 promoter activity in a light-dependent way. Activity of the D/C-4 promoter slightly increased in the dark and decreased in the light. Effect of light on the psbA promoter activity was not observed at all in mature chloroplasts. In vitro transcriptional analysis of the D/C-3 promoter with 5′ deletion mutations revealed that at least two cis elements which are located within the sequences of -78 to -47 and -46 to -29 of the transcription initiation site, respectively, act as enhancing elements in the D/C-3 promoter. The light-switching element of the transcription, however, was suggested to be located in the core promoter sequence downstream of the -35 element.
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  • 50
    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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  • 51
    ISSN: 1573-5028
    Keywords: cold temperature ; dehydration ; greening ; protein kinase ; Triticum aestivum/ ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have identified a new wheat PKABA1/-like protein kinase gene, TaPK3/, that is expressed in greening wheat seedlings. TaPK3 has high sequence homology (97% similarity with some sequence diversity at the 3' end) to the wheat PKABA1 protein kinase mRNA, which is upregulated by cold-temperature treatment, dehydration and abscisic acid (ABA). Use of a TaPK3 gene-specific probe has revealed that TaPK3 is differentially expressed with respect to PKABA1. TaPK3 mRNA accumulates in greening shoot tissue of wheat, but is not affected by dehydration, cold-temperature treatment or ABA. Based on sequence and expression differences, we conclude that expression of the PKABA1/-like protein kinases is not limited to stress responses.
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  • 52
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    Plant molecular biology 34 (1997), S. 643-650 
    ISSN: 1573-5028
    Keywords: callus ; crown tissue ; gene expression ; low temperature ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The low-temperature (2 °C)-specific wheat cDNA, pTACR7, represents a gene designated tacr7 from hard red winter wheat (HRWW; Triticum aestivum L. cv. Winoka). The term low-temperature-specific (LTS) is used because tacr7 is not induced by ABA or stresses such as salt, dehydration, and heat. pTACR7 was isolated by RT-PCR with mRNA from wheat crown tissue, the oligonucleotide primers derived from the barley cognate pHVCR8 (GenBank accession number L28091). Based on the deduced amino acid sequence, TACR7 is highly hydrophobic, with a single transmembrane domain and an amino acid bias for leucine (19%). Thus, the encoded protein TACR7 is unique among low-temperature-regulated wheat proteins described in the literature. Analysis of steady-state levels of tacr7 transcripts (630 nt) showed accumulation in wheat seedlings, crown tissue, and callus cultures after transfer from control (25 °C) to low temperature (2 °C). No detectable transcripts were observed by northern blot hybridization with pTACR7 probe from seedling or callus treated with ABA, salt, dehydration, or heat stress. tacr7 transcripts accumulated during 2 °C exposure to a greater amount in a freeze-resistant HRWW (FR; SDmut 16029) than in a freeze-susceptible HRWW (FS; SDmut 16169) crown tissue, with the largest difference between genotypes being 30% ± 3% at 3 weeks.
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  • 53
    ISSN: 1432-203X
    Keywords: Triticum aestivum L. ; wheat ; transformation ; biolistics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have developed a method for the accelerated production of fertile transgenic wheat (Triticum aestivum L.) that yields rooted plants ready for transfer to soil in 8–9 weeks (56–66 days) after the initiation of cultures. This was made possible by improvements in the procedures used for culture, bombardment, and selection. Cultured immature embryos were given a 4–6 h pre-and 16 h post-bombardment osmotic treatment. The most consistent and satisfactory results were obtained with 30 μg of gold particles/bombardment. No clear correlation was found between the frequencies of transient expression and stable transformation. The highest rates of regeneration and transformation were obtained when callus formation after bombardment was limited to two weeks in the dark, with or without selection, followed by selection during regeneration under light. Selection with bialaphos, and not phosphinothricin, yielded more vigorously growing transformed plantlets. The elongation of dark green plantlets in the presence of 4–5 mg/l bialaphos was found to be reliable for identifying transformed plants. Eighty independent transgenic wheat lines were produced in this study. Under optimum conditions, 32 transformed wheat plants were obtained from 2100 immature embryos in 56–66 days, making it possible to obtain R3 homozygous plants in less than a year.
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  • 54
    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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  • 55
    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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  • 56
    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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  • 57
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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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  • 58
    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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  • 59
    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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  • 60
    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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  • 61
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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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  • 62
    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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  • 63
    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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  • 64
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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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  • 65
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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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  • 66
    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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  • 67
    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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  • 68
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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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  • 69
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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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  • 70
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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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  • 71
    ISSN: 1432-2242
    Keywords: Key words Genetic resources ; Dynamic conservation ; Two-dimensional electrophoresis ; Artificial population ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    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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  • 72
    ISSN: 1432-2242
    Keywords: Key words Wheat landrace ; Triticum aestivum ; Powdery mildew resistance ; Monosomic analysis ; Gene location
    Source: Springer Online Journal Archives 1860-2000
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    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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  • 73
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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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  • 74
    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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    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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  • 76
    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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  • 77
    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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  • 78
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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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    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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    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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  • 81
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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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  • 82
    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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  • 83
    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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  • 84
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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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  • 85
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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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  • 86
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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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  • 87
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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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  • 88
    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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  • 89
    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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  • 90
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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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  • 91
    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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  • 92
    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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  • 93
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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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  • 94
    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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  • 95
    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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  • 96
    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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  • 97
    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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  • 98
    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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  • 99
    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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  • 100
    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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