Author
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Burton, Joseph |
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Submitted to: Foreign Agriculture Organization Proceedings
Publication Type: Proceedings Publication Acceptance Date: 9/3/2008 Publication Date: 11/24/2008 Citation: Burton, J.W. 2008. Quantitative genetics in soybean: Is dominance important?. Foreign Agriculture Organization Proceedings. Interpretive Summary: In soybeans, dominance of genes is generally considered to be of little importance. Genetic variation due to genetic dominance diminishes rapidly with inbreeding. Self-pollination is the natural way that soybeans reproduce. So inbreeding, through the self-pollination process, proceeds at a rapid pace. As a result, the soybean varieties, that farmers grow, are highly inbred. Yet, there is good evidence from soybean breeding research reported in literature, that hybrid vigor, one result of genetic dominance, is present in the progeny from the cross-fertilization of some inbred soybean lines. Hybrid vigor in the second inbred generation could be a simple and useful way to predict the value of particular parental combinations. This has been previously proposed by wheat and barley breeders and used with some reported success. Technical Abstract: In soybeans, dominance is generally considered to be non-existent or of little importance. Because genetic variation due to dominance dissipates rapidly with inbreeding, dominance would presumably not be useful in breeding soybean cultivars which are highly inbred. Yet, there is evidence for heterosis in soybean, and inbreeding depression (evidence for dominance) has also been reported. Heterosis can have several genetic causes. These include a greater number of favorable (dominant) alleles in the F1 hybrid then in the two parents singly; linked dominant alleles that complement each other by masking less favorable alleles, and/or through duplicate gene interaction; and alleles that produce similar effects as homozygotes, but interact when heterozygous or heterologous. All of the above can be fixed in pure-lines except heterosis due to single locus allelic interaction. Thus, heterosis measured in F2 bulk performance may be a useful way to predict the value of a cross. Early generation testing may also be useful if it can be economically incorporated in a practical breeding program. |
