QTL underlying crop adaptation to mega-environments in soybean

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The use of exotic germplasm to improve the productivity of crop plants has been limited due to relatively low and variable success that has been encountered, depending on the species and germplasm used. In soybean, after the initial introduction of ancestral lines in the last century, there has been little use of breeding materials exchanged between the Chinese (centre of origin and diversity) and North American soybean breeding programs, even for materials coming from similar growing regions. Typically, the lack of environmental adaptation in non-host environments has hampered progress in using exotic germplasm resulting in a rare recovery of, or surpassing, of the adapted parent's yield in the progeny. If seed yield is the ultimate measure of a given crop's adaptation potential, it does not seem to be explained solely by the maturity group or the latitude the introduced materials came from. Within the previous NSERC Discovery grant, we have determined that a ratio of universal vs. continent-specific quantitative trait loci (QTL) appears to drive the forces of adaptation to mega-environments. In this proposal, we will attempt to address the following questions. Does the mega-environment in which the breeding population is developed influence a non-random selection of genotypes, even when breeding methods that assume randomness of selection are practiced? Is segregation distortion caused by non-random selection of genotypes, even when breeding methods assume randomness? How important a role do markers that show segregation distortion play in the expression of yield QTL? What is the role of interacting QTL (epistasis) in determining adaptation? Can a portion of the observed diversity in QTL alleles for seed and agronomic traits in the Chinese germplasm be explained in part by the greater use of the wild soybean progenitor, Glycine soja, by the Chinese soybean breeding programs? The conceptual significance of this research is that the determining of the underlying genetic principles of crop adaptation may aid in the development of a more strategic and genetically-based introgression of new genetic variation into a number of species.