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  • 1
    Electronic Resource
    Electronic Resource
    The genetical basis of hybrid vigour in a highly heterotic cross of Nicotiana tabacum (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 1027-1031 
    Details
    ISSN: 1432-2242
    Keywords: Basic generations ; Epistasis ; Maternal effects ; Recombinant inbreds ; Triple test cross
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genetical control of F1 heterosis, observed in a cross of desirable Nicotiana tabacum varieties, was investigated by analysing the data of the basic generations, triple test cross-families and random samples of doubled haploids (DH) and single-seed descent (SSD) lines. Analyses of the first-degree statistics revealed a complex control underlying the genetic variation, including the presence of epistasis, linkage, maternal effects and their interactions, in addition to the additive and dominance effects of the genes segregating in the cross. These analyses identified gene dispersion, directional dominance, and duplicate epistasis, as the main causes of heterosis. The triple test-cross analysis also confirmed the presence of non-allelic interactions and indicated that the dominance ratio, although inflated by epistasis, is consistently partial for all the traits. The extent of transgression in the recombinant inbred lines finally established unequivocally that, as in numerous other crosses, gene dispersion and unidirectional, but partial, dominance are the true causes of heterosis in this cross too.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224534
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The nature of gene action in a Nicotiana rustica cross revealed by the recombinant inbred and second-cycle hybrid analysis (1997)
    Springer
    Theoretical and applied genetics 94 (1997), S. 664-673 
    Details
    ISSN: 1432-2242
    Keywords: Key words Dominance ratio ; Genetic variation ; Heritability ; Non-allelic interaction ; Transgression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A unique set of data recorded on 60 randomly extracted single-seed-descent (F∞) lines of a highly heterotic cross between two varieties of Nicotiana rustica and their 870 reciprocally produced pairwise crosses, the second-cycle hybrids (SCH), are analysed to investigate the true nature of genetical control in the cross and the results are compared with those in earlier publications. The analysis revealed that epistasis, genotype-by-micro-environmental interaction, maternal effects and linkage are significant for several characters and the additive and non-additive components of variation take large values for all of the traits. Epistasis is predominantly duplicate and not complementary. Dominance is high but partial, all estimates of dominance ratio lying between 0.5 and 0.9. Dominance is predominantly unidirectional for leaf length, leaf width and final height, while for the remaining traits, some genes show ambidirectional dominance, although the incidence of unidirectional dominance is much higher throughout. The direction of dominance is predominantly for the increased score, except for flowering time where alleles conferring earliness are up to five times more frequently dominant. The present study has also confirmed that the F2 and SCHi distributions are very similar and that the former can be used to predict the transgression in the latter with confidence. The reduced range of the SCH i families compared to the recombinant inbreds, further indicated that heterosis among many of the SCHi is due to gene dispersion and there is little evidence for the presence of over-dominance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050464
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Fast and reliable genotype validation using microsatellite markers in Arabidopsis thaliana (1999)
    Springer
    Theoretical and applied genetics 98 (1999), S. 462-464 
    Details
    ISSN: 1432-2242
    Keywords: Key words Arabidopsis ; Microsatellites ; DNA markers ; PCR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In this paper we show how rogue genotypes in the parental stocks or contaminants among the crossed progeny of Arabidopsis thaliana can be readily identified and excluded from the breeding process using microsatellite markers derived from a small quantity of intact leaf tissue which has been alkali-treated. This method is fast and cost effective as it does not require DNA extraction, is highly reliable, and is less damaging to small plants where only limited quantities of plant tissue are available. Furthermore, a large number of samples can be processed in 1 day, facilitating the identification process prior to selfing or crossing the plants. In addition, the procedure could potentially be automated since no centrifugation is required.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051092
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Repeatability of stability estimators for downy mildew incidence in pearl millet (1985)
    Springer
    Theoretical and applied genetics 70 (1985), S. 102-106 
    Details
    ISSN: 1432-2242
    Keywords: Downy mildew ; Pearl millet ; Stability parameters ; Repeatability ; Multilocation testing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Repeatability of mean downy mildew (Sclerospora graminicola (Sacc.) Schroet.) incidence, regression coefficients and deviation mean squares were investigated for 25 pearl millet (Pennisetum typhoides (Burm.) Stapf. & Hubb.) genotypes in 20 environments by correlating arrays of these stability parameters over subsets of the 20 environments arranged according to the year-wise, random, stratified and extreme methods of environmental division. Correlation coefficients between arrays of mean downy mildew incidence from different pairs of subsets ranged from 0.57 to 0.98 and those of deviation mean squares from 0.58 to 0.96 indicating good repeatability of these parameters. Arrays of regression coefficients from different subsets, on the other hand, showed correlation coefficients that ranged from −0.58 to 0.96. Apparently, the regression index of stability was not repeatable for the genotypes and environments studied. Therefore, in order to identify a widely adapted genotype, testing is required to be carried out over a wider range of environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00264490
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    Paper (German National Licenses)
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