Characterization of a Mini-Core Collection of Wild Soybean (Glycine soja) Used for Applied Breeding Research.

The limited genetic diversity 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 (18 accessions), Japan (22 accessions), Russia (11 accessions), South Korea (28 accessions), and Taiwan (1 accession). The 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.  The selected PIs were grown during 2013 at the Bradford Research and Extension Center in Columbia, MO, and at two locations in North Carolina, 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 concentrations, seed oil and fatty acid concentrations, and seed carbohydrate and oligosaccharide concentrations.  The PIs were also screened for salt and flood tolerance at the Fisher Delta Research Center in Portageville, MO during 2013 and 2014.  Genotype was a significant (p < 0.0001) source of variation for maturity date, seed weight, and seed protein, sucrose, and stachyose concentrations.  A genome-wide association mapping study will be performed to identify major quantitative trait loci controlling the evaluated traits in these PIs.  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.