Effects of selective genetic introgression from wild soybean to soybean

Commercial soybean [Glycine max (L.) Merr.] breeding in the U.S. currently relies on a narrow genetic base in which more than half of the genetic contribution, calculated by pedigree analysis, comes from only 5 ancestral lines. For decades, but more intensely in recent years, efforts have been made to incorporate exotic soybean germplasm into the breeding pool. Although wild soybean (G. soja Seib. & Zucc.) is genetically much more diverse than soybean, much less effort has been devoted to utilizing wild soybean in soybean breeding. The objectives of this research are to identify high yielding lines derived from crosses between 5 wild soybean accessions and soybean cultivars; and determine if there are differences in the genetic contributions of each wild soybean parent. Each wild soybean was crossed to Williams 82 and the F1 plants were backcrossed to Williams 82. The BC2 parent lines were developed through intensive family selection and backcrossed to Williams 82. Family selection beginning in the F2 generation was used to develop lines from PI 507807 and PI 549046. The lines from PI 479767 and PI 483461 were selected by early generation testing through yield testing F2 lines in the F3 and F4 generation. The lines derived from PI 65549 were developed from an SSD population. Field evaluation of the derived lines in 6 environments in 2011 and 4 environments in 2012 identified lines that are not significantly different from their recurrent parents as well as checks for yield. Genotyping the experimental lines and all the parental lines using 1536 SNP markers with the Illumina GoldenGate assay, we found unique contributions being made by the G. soja parents. Also, alleles that are consistently introgressed from the G. soja parents into all derived lines were identified. Despite intense selection pressure to recover good agronomic types, an average of 13% of SNP alleles in the derived lines came from the G. soja parents