Genetic contribution of foreign germplasm to elite Chinese soybean (Glycine max) cultivars revealed by SSR markers

Simple sequence repeats (SSR) marker analysis, combined with pedigree analysis, was carried out to trace the genetic constitutes of Suinong 14 and Hefeng 25 in assessing the contribution of foreign germplasm to those elite cultivars. The overall goal is to accumulate information for further effective utilization of foreign germplasm in Chinese soybean breeding programs. SSR clustering results indicated that the genetic base of elite Chinese soybean cultivars, including Suinong 14 and Hefeng 25, were broadened and enhanced via introduction of Amsoy from the U.S. and Shishengchangye from Japan. The pedigree analysis showed a very high coefficient of parentage between Shishengchangye and Hefeng 25, between Shishengchangye and Suinong 14, and between Amsoy and Suinong 14. The genetic similarity between Suinong 14 and Hefeng 25 was 60.58%. Among 20 linkage groups, more genomic regions were transferred from Hefeng 25 to Suinong 14 in linkage group (LG) I, L and C2 than other LGs. Among the unique alleles of foreign parents, five specific loci in Amsoy were transferred to Suinong 14, and three loci from Shishengchangye to Suinong 14. Some SSR loci were proved to be correlated with phenotypes: two loci for seed size introgressed from Shishengchangye to Suinong 14, and one locus for protein content from Amsoy to Suinong 14. These results indicate that the two foreign parents might have important contributions in the development of Suinong 14 and Hefeng 25.