Confirmation of SSR Markers and QTL for Seed Calcium Content and Hardness of Soybean

Seed calcium content and hardness constitute determining characteristics of soybean [Glycine max (L.) Merr.] texture affecting soyfood quality. Molecular markers linked to these traits will accelerate breeding of soybeans for the soyfood market through the use of marker-assisted selection (MAS). Confirmation of linked markers and validation of quantitative trait loci (QTL), prior to their application throughMAS, are the keys. The objectives of this study were to confirm previously reported QTL for calcium content and seed hardness and investigate the relationship between these traits. Evaluation of seven recombinant inbred line (RIL) populations with different genetic backgrounds, grown in two Arkansas locations for 2 years, showed inconsistent correlations between these traits. In general, a positive correlation was found in most of the populations and correlation was significant in six populations. Combined data showed a positive correlation between calcium content and seed hardness (r = 0.23 -0.49). Furthermore, previously reported QTL for calcium content and/or hardness were evaluated in six different sub-populations and stable markers across environments were identified for potential use in MAS. Based on our results, markers Satt267 and Sat_345 on chromosome 1, Sat_288 on chromosome 7, Sat_228, Satt341, and Sat_392 on chromosome 8, Satt547 on chromosome 16, and Satt002 on chromosome 17, are reliable for calcium content selection; whereas, Satt267, Satt680, Satt341, and Sct_010 on chromosomes 1, 7, 8, and 19, respectively, can be used for selection for seed hardness. Findings of this research will facilitate MAS for seed calcium content and hardness in breeding programs aimed at improving food-grade soybeans.