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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Biochemical genetics 30 (1992), S. 491-502 
    ISSN: 1573-4927
    Keywords: Glycine max ; malate dehydrogenase ; deletions ; chlorophyll deficient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Three chlorophyll-deficient mutants (CD-1, CD-2, and CD-3), derived from the progeny of independent germinal revertants from thew4-mutable soybean line [Glycine max (L.) Merrill], were characterized genetically. Electrophoretic analyses indicated that these lines lacked two of three mitochondrial malate dehydrogenase isozymes (MDH−). The absence of two MDH bands was conditioned by a recessive allele at a locus designatedMdh1. All three CDs were allelic to each other and to T253, a Harosoy isoliney20-k2 MDH− from the Genetic Type Collection. The MDH− phenotype and the yellow-green plant phenotype were each inherited as single recessive alleles. No recombination between the two traits was found in nine F2 populations from crosses of the CDs by wild-type soybean lines. Complete linkage of theMdh1 andy20 loci suggested that the mutations in the chlorophyll-deficient lines were deletions. Phenotypic differences among the CDs suggested that the deletions may have different endpoints. The chromosomal aberrations were not large enough to affect transmission ofy20 andMdh1 mutant alleles through the pollen or ovule. CD-1, CD-2, and CD-3 were added to the Soybean Genetic Type Collection as T323, T324, and T325, respectively.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2242
    Keywords: Exotic germplasm  ;  Selection of parents  ;  Testcross
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Methods for identifying germplasm carrying alleles with the potential to improve a particular single-cross hybrid have been proposed and discussed in recent years. There is a need for similar methods to be used in breeding crops for which pure-line cultivars, rather than hybrids, are the goal. The objective of this research was to develop a method to identify germplasm lines with the potential to contribute favorable alleles not present in a specified pure line or set of pure lines. Given a set of adapted pure lines to be improved and a set of germplasm lines , the procedure consists of producing all f×m possible hybrids and evaluating them along with the parents. The testcross statistic is defined by , where and represent the performance of the adapted line, the germplasm line, and their hybrid, respectively. The statistic is the mean value of over all adapted parents . If , where =the mean degree of dominance, then measures the potential for alleles from to improve , and measures the potential for alleles from to improve the set . Use of data on soybean and peanut hybrids published by other researchers suggests that the value assumed for has little effect on the chosen. The ability of the and statistics to identify germplasm strains carrying rare favorable alleles should be assessed in empirical studies.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2242
    Keywords: Exotic germplasm ; Selection of parents ; Testcross
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Methods for identifying germplasm carrying alleles with the potential to improve a particular single-cross hybrid have been proposed and discussed in recent years. There is a need for similar methods to be used in breeding crops for which pure-line cultivars, rather than hybrids, are the goal. The objective of this research was to develop a method to identify germplasm lines with the potential to contribute favorable alleles not present in a specified pure line or set of pure lines. Given a set of adapted pure lines (A 1, A 2 ..., A m) to be improved and a set of germplasm lines (P 1 P 2 ..., P f), the procedure consists of producing all f x m possible hybrids and evaluating them along with the parents. The testcross statistic T ij is defined by T ij=γ(F ij−A j)+(1−γ) (F ij−P i), where A j, P i, and F ij represent the performance of thej th adapted line, the i th germplasm line, and their hybrid, respectively. The statistic $$\bar T_i = \left( {{1 \mathord{\left/ {\vphantom {1 m}} \right. \kern-\nulldelimiterspace} m}} \right)\sum {\left( {T_{ij} } \right)} $$ is the mean value of T ij over all adapted parents A j. If γ=(1/2)(1+d′), where d′ = the mean degree of dominance, then T ij measures the potential for alleles from P i to improve A j and $$\bar T_i $$ measures the potential for alleles from P i to improve the set A 1, A 2 ..., A m. Use of data on soybean and peanut hybrids published by other researchers suggests that the value assumed for d′ has little effect on the P i chosen. The ability of the T ij and $$\bar T_i $$ statistics to identify germplasm strains carrying rare favorable alleles should be assessed in empirical studies.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 542-551 
    ISSN: 0192-253X
    Keywords: Glycine max ; Transposable element ; Transposon tagging ; Genetic instability ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: An unstable mutation for anthocyanin pigmentation in soybean (Giycine max [L.] Merr.) was identified in 1983. The mutability is conditioned by an allele at the w4 locus that is recessive to wild type. The population containing the mutable allele is known as the w4-mutable line. Most plants in the line have chimeric flowers with purple sectors on a near-white background. The mutable allele yields germinal revertants at a rate that varies from 5 to 10% per generation, and the revertant alleles are stable. Approximately 1% of the progenies derived from germinal revertant plants contain mutations at other loci These features, as well as the occurrence of pale flower phenotypes and changes of state, suggest that a transposable element system is producing the unstable phenotype.Several new mutants were isolated in an experiment designed to tag loci. The first three chlorophyll-deficient mutants found (CD-1, CD-2, and CD-3) are inherited as single-gene recessives. Each of the mutants lacks the same two mitochondrial malate dehydrogenase (MDH) bands. No recombination has been detected between the MDH phenotype and the chlorophyll-deficient phenotype. Genetic data indicate that the three mutants are allelic, and additional evidence suggests that each of the CD mutants is the result of a deletion. In the CD-1, CD-2, and CD-3 mutants, the deletions result in the silencing of an MDH locus, atypical chloroplast development, and an altered chlorophyll composition. Additional mutants for root necrosis, partial and near sterility, chlorophyll deficiency, and flower color isolated from the transposon tagging study have provided material for future research.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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