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The Genetic Framework of Plant Breeding
J. L. Jinks
Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Vol. 292, No. 1062, The Manipulation of Genetic Systems in Plant Breeding (Jun. 10, 1981), pp. 407-419
Published by: Royal Society
Stable URL: http://www.jstor.org/stable/2395759
Page Count: 13
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The phenotypic variation that the breeder must manipulate to produce improved genotypes typically contains contributions from both heritable and non-heritable sources as well as from interactions between them. The totality of this variation can be understood only in terms of a methodology such as that of biometrical genetics - an extension of classical Mendelian genetics that retains all of its analytical, interpretative and predictive powers but only in respect of the net or summed effects of all contributing gene loci. In biometrical genetics the statistics that describe the phenotypic distributions are themselves completely described by heritable components based on the known types of gene action and interaction in combination with non-heritable components defined by the statistical properties of the experimental design. Biometrical genetics provides a framework for investigating the genetical basis and justification for current plant breeding strategies that are typified by the production of F1 hybrids at one extreme and recombinant inbred lines at the other. From the early generations of a cross it can extract estimates of the heritable components of the phenotypic distributions that provide all the information required to interpret the cause of F1 heterosis and predict the properties of any generation that can subsequently be derived from the cross. Applications to crosses in experimental and crop species show that true over-dominance is not a cause of F1 heterosis, although spurious overdominance arising from linkage disequilibria and non-allelic interactions can be. Predictions of the phenotypic distributions and ranges of recombinant inbred lines that should be extractable from these crosses are confirmed by observations made on random samples of inbred families produced from them by single seed descent. Within these samples, recombinant inbred lines superior to existing inbred lines and their F1 hybrids are observed with the predicted frequencies.
Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences © 1981 Royal Society