Characterization and Genome-Wide Association Mapping of Seed Composition and Agronomic Traits Using a Mini-Core Collection of a Wild Soybean (Glycine soja).

The low genomic variation of U.S. soybean [Glycine max (L.) Merill] cultivars restrains the improvement of grain yield, seed quality, and other agronomic traits. Recently, a substantial effort to utilize wild soybean (Glycine soja Siebold & Zucc.) in applied soybean breeding programs has been undertaken to introduce novel genetic diversity into new cultivars. The objective of this research is to evaluate the phenotypic diversity among 80 G. soja plant introductions (PIs) collected in China, Japan, Russia, South Korea, and Taiwan and identify marker associations using a genome-wide association mapping approach. These PIs were chosen to represent maximal diversity based on their genetic differences using a cluster analysis of the entire USDA collection of G. soja PIs and the Illumina SoySNP50K SNP data. Field tests were conducted at one location in Missouri and at two locations in North Carolina during three years, 2013, 2014, and 2015, in a randomized complete block design with three replications. The phenotypic data collected in the field and lab included: maturity date, seed weight, seed protein and amino acid content, seed oil and fatty acid content, and seed carbohydrate and oligosaccharide content. Analyzing the data from one location in Missouri during 2013 and 2014, we found that genotype was a significant (p < 0.0001) source of variation for maturity date, seed weight, and seed protein and oil. A genome-wide association mapping study (GWAS) was performed to identify significant marker associations with all measured traits. The GWAS results identified one SNP on Gm06, one SNP on GM07, and one SNP on GM10 associated with maturity, seed oil, and seed protein, respectively. With the data collected from this research, soybean breeders can select PIs for use as parents in their breeding program for a variety of research objectives concerning many important agronomic and seed compositional traits.