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  • wheat  (109)
  • Wheat  (89)
  • Springer  (198)
  • American Association of Petroleum Geologists (AAPG)
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  • 1
    ISSN: 1573-1561
    Keywords: Cover crops ; wheat ; Triticum aestivum ; soybean ; Glycine max ; soil extracts ; germination bioassays ; phenolic acids ; hydroxamic acids ; allelopathy ; slope analysis ; ivy-leaved morning glory ; Ipomoea hederacea ; crimson clover ; Trifolium incarnalum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The primary objective of this research was to determine if soil extracts could be used directly in bioassays for the detection of allelopathic activity. Here we describe: (1) a way to estimate levels of allelopathic compounds in soil; (2) how pH, solute potential, and/or ion content of extracts may modify the action of allelopathic compounds on germination and radicle and hypocotyl length of crimson clover (Trifolium incarnatum L.) and ivyleaved morning glory (Ipomoea hederacea L. Jacquin.); and (3) how biological activity of soil extracts may be determined. A water-autoclave extraction procedure was chosen over the immediate-water and 5-hr EDTA extraction procedures, because the autoclave procedure was effective in extracting solution and reversibly bound ferulic acid as well as phenolic acids from wheat debris. The resulting soil extracts were used directly in germination bioassays. A mixture of phenolic acids similar to that obtained from wheat-no-till soils did not affect germination of clover or morning glory and radicle and hypocotyl length of morning glory. The mixture did, however, reduce radicle and hypocotyl length of clover. Individual phenolic acids also did not inhibit germination, but did reduce radicle and hypocotyl length of both species. 6-MBOA (6-methoxy-2,3-benzoxazolinone), a conversion product of 2-o-glucosyl-7-methoxy-1,4-benzoxazin-3-one, a hydroxamic acid in living wheat plants, inhibited germination and radicle and hypocotyl length of clover and morning glory. 6-MBOA, however, was not detected in wheat debris, stubble, or soil extracts. Total phenolic acids (FC) in extracts were determined with Folin and Ciocalteu's phenol reagent. Levels of FC in wheat-conventionaltill soil extracts were not related to germination or radicle and hypocotyl length of either species. Levels of FC in wheat-no-till soil extracts were also not related to germination of clover or morning glory, but were inversely related to radicle and hypocotyl length of clover and morning glory. FC values, solute potential, and acidity of wheat-no-till soil extracts appeared to be independent (additive) in action on clover radicle and hypocotyl length. Radicle and hypocotyl length of clover was inversely related to increasing FC and solute potential and directly related to decreasing acidity. Biological activity of extracts was determined best from slopes of radicle and hypocotyl length obtained from bioassays of extract dilutions. Thus, data derived from the water-autoclave extraction procedure, FC analysis, and slope analysis for extract activity in conjunction with data on extract pH and solute potential can be used to estimate allelopathic activity of wheat-no-till soils
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 98 (1999), S. 226-233 
    ISSN: 1432-2242
    Keywords: Key words Molecular mapping ; Wheat ; Resistance ; Defense response genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Defense response (DR) genes are a broad class involved in plant defense. In this study we mapped 36 probes representing seven classes of defense response genes. This collection of probes represents genes involved in the hypersensitive response (HR), pathogenesis-related (PR) genes, genes for the flavonoid metabolic pathway, genes encoding proline/glycine-rich proteins, ion channel regulators, lipoxygenase, lectin, and others. Using nullisomic-tetrasomic lines of ‘Chinese Spring’, we were able to assign at least 167 loci to the 21 chromosomes of wheat. Homoeologous group 7 chromosomes possessed the most DR loci followed by group 2. Sixty-two loci were placed on existing genetic linkage maps of wheat. Map locations indicated that the DR gene loci are not randomly distributed throughout the wheat genome, but rather are located in clusters and/or in distal gene-rich regions of the chromosomes. Knowledge of the chromosomal locations and genome organization of DR genes will be useful for candidate gene analysis of quantitative trait loci.
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  • 3
    ISSN: 1573-5036
    Keywords: aluminium ; electron microscope ; light microscope ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Root tips from aluminium (Al) tolerant (Waalt) and Al sensitive (Warigal) wheat (Triticum aestivum (L). Thell.) cultivars exposed to low concentrations of Al (10 μM) for 10, 24 and 72 hours were examined under the light and electron microscope. After fixing and embedding, longitudinal and transverse thin and ultrathin sections were cut. There was no evidence of Al damage to the root tips of the Al tolerant cultivar under both the light and electron microscope. For the Al sensitive cultivar, Al had no observable effect on the root tips 10 hours after Al addition when examined under the light microscope. When examined under an electron microscope, electron dense globular deposits were observed between the cell wall and cell membrane of the epidermal cells. There was not obvious damage to the cell cytoplasm. Two or 3 days after Al addition, light microscopy showed that the cells in the root tips had become swollen and extensively vacuolated. The tissues appeared disorganised and degenerate, particularly in the epidermis and outer cortical cells. The electron microscope also revealed a thickening of the cell wall. The cell wall was broken down, particularly in the epidermis in the region 4–6 mm from the root tip. The tissue in the meristematic area was largely intact.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 16 (1988), S. 137-155 
    ISSN: 1573-0867
    Keywords: Superphosphate ; rock phosphate ; wheat ; oats ; barley ; field experiment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nine soil tests for phosphate were evaluated for predicting the yield and P content of wheat, barley and oats grown on a sandy soil in Western Australia: Olsen, modified Olsen 1 (soil:solution ratio 1:5), modified Olsen 2 (soil:solution ratio 1:50), Colwell, Bray 1, Bray 2, modified Bray 2T (shaking time 10 minutes), modified Bray 2C (pH 3.7) and lactate. The soil had been fertilized 5 years previously with 20 levels each of superphosphate (OSP, range 0 to 400 kg P ha−1) and Queensland rock phosphate (QRP, range 0 to 20 000 kg P ha−1). For each species and fertilizer taken separately, all the tests, except for lactate, gave a good prediction of yield. When data for OSP and QRP were pooled, Bray 2 and modified Bray 2T tests were unsatisfactory predictors of both yield and P content. A linear relationship (P 〈 0.05) between mean soil tests value (χ) and the standard deviation (σ χ ) of the test value was observed for each soil test. For QRP, the results for lactate were the most variable (i.e.σχ/χ was greatest) followed by modified Olsen 2 〉 Bray 1 〉 Bray 2 〉 Olsen 〉 modified Bray 2C 〉 modified Olsen 1 〉 modified Bray 2T 〉 Colwell. The order for OSP fertilized soil was Bray 1 〉 modified Bray 2T 〉 Bray 2 〉 Olsen 〉 Colwell 〉 modified Bray 2C 〉 modified Olsen 1 〉 lactate 〉 modified Olsen 2. For combined OSP and QRP data, the results of the Olsen 1 and Colwell extractions were the least variable. Errors in the prediction of yield (σ Y ) for all crops resulting from an error in soil test values (σχ) were calculated. For OSP-fertilized soil variability in values for the Bray-1 test provided the highest error (about 16%) in the prediction of the yield, followed by Bray 2 (12%) 〉 Bray 2T (10%) 〉 Olsen (8%) 〉 Colwell (7%) 〉 modified Bray 2C (6%) 〉 lactate (4%). Maximum error was at yields of about 65% of maximum yield. For soil fertilized with QRP, lactate provided the highest error (about 10%) in the prediction of yield, followed by the other tests (〈 6%). Maximum error was at yields of about 35% of maximum yield. The Colwell soil test gave the most accurate overall prediction of yield for both fertilizers.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 3 (1990), S. 70-76 
    ISSN: 1432-2145
    Keywords: Wheat ; Maize ; Hybridization ; Fertilization ; Karyogamy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cytological events in the first 12 h after pollination were studied in crosses between the hexaploid wheat genotype Chinese Spring and the maize genotype Seneca 60. A pollen tube was first observed in the embryo sac 4 h after pollination, and maize sperm nuclei were first observed in the embryo sac after 5 h. On 29 occasions two, and on 1 occasion three, pollen tubes penetrated the embryo sac. Four categories of aberration limiting the frequency of fertilization were identified: (1) in 20% of florets no pollen tube reached the embryo sac; (2) in at least 1.9% the pollen tube severely damaged the wheat egg cell and polar nuclei; (3) in 33% the maize sperm nuclei were not released from the pollen tube; and (4) in 16% the sperm nuclei were released into the embryo sac but failed to move to either of the wheat gametes. In the remaining 29% sperm nuclei were more often found in the egg cell than at the polar nuclei. The results suggest that karyogamy occurs with very high efficiency when a sperm nucleus reaches the egg cell, but with only about 50% efficiency when a sperm nucleus reaches the polar nuclei.
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  • 6
    ISSN: 1573-4927
    Keywords: wheat ; seed protein genes ; restriction-fragment length polymorphism, prolamins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Restriction enzyme digests of DNA from nullisomic-tetrasomic and intervarietal chromosome substitution lines of wheat were probed with a high molecular weight (HMW) glutenin cDNA. Three restriction endonucleases were used to investigate restriction-fragment differences among five wheat varieties. The results suggest that the hybridizing fragments contain single gene copies and permit the identification of the subunit encoded by each gene. Restriction-fragment variation associated with previously established allelic differences between varieties was observed. Also, there is a clear relationship between the electrophoretic mobility of a HMW subunit and the length of the central repetitive section of the gene encoding it. These results are discussed with reference to the evolution of the HMW glutenin gene family and the uses of restriction-fragment variation in plant breeding and genetics.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 73 (1987), S. 403-409 
    ISSN: 1432-2242
    Keywords: Wheat ; Maize ; Crossability genes ; Chromosome elimination ; Haploids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Dominant alleles of the Kr1 and Kr2 genes reduce the crossability of hexaploid wheat with many alien species, including rye and Hordeum bulbosum, with Kr1 having the greater effect. However, a cytological study of wheat ovaries fixed 48 h after pollination showed that the wheat genotypes ‘Highbury’ (kr1, Kr2) and ‘Chinese Spring (Hope 5B)’ (kr1, kr2) were crossable with ‘Seneca 60’ maize, fertilization occurring in 14.4 and 30.7% of embryo sacs respectively. The latter figure was similar to the 29.7% fertilization found in ‘Chinese Spring’ (kr1, kr2). Most embryo sacs in which fertilization occurred contained an embryo but lacked an endosperm and where an endosperm was formed it was usually highly aberrant. All three wheat x maize combinations were karyotypically unstable and rapidly eliminated maize chromosomes to produce haploid wheat embryos.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 79 (1990), S. 294-296 
    ISSN: 1432-2242
    Keywords: Grain esterase ; Wheat ; Isoelectric focussing ; Isozymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Isoelectric focussing in alkaline pH gels has permitted the identification of a new homoeoallelic series of genes,Est-6, encoding grain esterases in bread wheat,Triticum aestivum. Nullisomic analysis located these genes to the short arms of the homoeologous group 2 chromosomes. A search for polymorphism withinEst-6 revealed null alleles at each ofEst-A6,Est-B6 andEst-D6. A further homoeolocus,Est-M6, is present on chromosome arm2MS ofAegilops comosa.
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  • 9
    ISSN: 1432-2242
    Keywords: Wheat ; Tripsacum dactyloides ; Wide crosses ; Fertilization ; Embryo formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Hexaploid wheat variety Fukuho was crossed with Tripsacum dactyloides (2n=4x=72). The total fertilization frequencies for the egg cell, polar nuclei, and both, were 58.3%, 26.8% and 58.9% of the 168 ovaries examined. However, the fertilization frequency of single polar nuclei was much lower at only 0.6%. The total frequency of fertilization was higher than that in wheat x maize crosses. A total of 49 hexaploid wheat varieties, including Hope carrying the dominant genes Kr1 and Kr2, were crossed with T. dactyloides, and most gave embryos. The embryoformation frequencies ranged from 0.5% to 59.0%. A higher frequency of 32.0% embryo formation was obtained following pollination of the variety Hope. In comparison with embryo formation in wheat x maize crosses the difference of embryo-formation frequencies between the two crosses was significant. The results of high frequencies of fertilization and embryo formation in wheat x T. dactyloides crosses indicated that the Kr genes are as inactive in wheat x T. dactyloides, as they are in wheat x maize crosses, and also that the efficiency of fertilization and embryo formation is higher in wheat x T. dactyloides than in what x maize crosses. The potential of wheat x T. dactyloides crosses for wheat haploid production and wheat improvement is discussed.
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  • 10
    ISSN: 1432-2242
    Keywords: HMW glutenin subunit genes ; cDNA clones ; Tandem DNA repeats ; Chromosomal location ; Gene copy number ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary cDNA clones encoding wheat HMW glutenin subunits have been isolated from a cDNA bank made to poly A+ RNA from developing wheat endosperm var. Chinese Spring. One such clone, pTag 1290, has enabled us to identify the HMW glutenin mRNA species. The DNA sequence of this clone has been partially determined and it contains several tandem DNA repeats. The sequence is discussed in relation to the generation of the HMW glutenin subunit gene family. Analysis of the organization of the HMW glutenin sequences in the wheat genome revealed that the genes encoding HMW glutenin subunits exist in low copy number and are located on the long arm of each of the homoeologous group 1 chromosomes.
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