Genome composition changes due to long term selection by soybean breeders

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Continued improvement of soybean varieties relies on sufficient genetic variation between parents to produce a population of individuals in which there is enough phenotypic variation to improve traits of interest. As phenotypic variation is positively associated with genetic diversity (Moose and Mumm 2008) it is important for a soybean breeding program to maintain a sufficient level of genetic diversity for continued genetic gain of a particular trait. In addition, developing soybean varieties for niche markets is an important objective for Canadian soybean breeders. This requires germplasm sources to have genetic diversity not only for traits such as yield, but also value-added traits such as food grade properties or nutraceutical compounds. The recent advancements in genomic technologies allow for unprecedented capabilities when investigating whole-genome changes to a species. By applying these technologies to pedigrees of a breeding program, the specific changes in the soybean genome due to long-term breeder selection can be studied. First, by genotyping the members of a pedigree, the changes in genetic diversity over generations of breeding activity can be characterized. Secondly, the transmission of chromosomes can be tracked and changes in allelic composition over generations and selection cycles can be determined.