Genetic mapping and validation of the loci controlling 7S α' and 11S A-type storage protein subunits in soybean [Glycine max (L.) Merr.]

Four soybean storage protein subunit QTLs were mapped using bulked segregant analysis and an F-2 population, which were validated with an F-5 RIL population. The storage protein globulins beta-conglycinin (7S subunit) and glycinin (11S subunits) can affect the quantity and quality of proteins found in soybean seeds and account for more than 70% of the total soybean protein. Manipulating the storage protein subunits to enhance soymeal nutrition and for desirable tofu manufacturing characteristics are two end-use quality goals in soybean breeding programs. To aid in developing soybean cultivars with desired seed composition, an F-2 mapping population (n = 448) and an F-5 RIL population (n = 180) were developed by crossing high protein cultivar 'Harovinton' with the breeding line SQ97-0263_3-1a, which lacks the 7S alpha', 11S A(1), 11S A(2), 11S A(3) and 11S A(4) subunits. The storage protein composition of each individual in the F-2 and F-5 populations were profiled using SDS-PAGE. Based on the presence/absence of the subunits, genomic DNA bulks were formed among the F-2 plants to identify genomic regions controlling the 7S alpha' and 11S protein subunits. By utilizing polymorphic SNPs between the bulks characterized with Illumina SoySNP50K iSelect BeadChips at targeted genomic regions, KASP assays were designed and used to map QTLs causing the loss of the subunits. Soybean storage protein QTLs were identified on Chromosome 3 (11S A(1)), Chromosome 10 (7S alpha' and 11S A(4)), and Chromosome 13 (11S A(3)), which were also validated in the F-5 RIL population. The results of this research could allow for the deployment of marker-assisted selection for desired storage protein subunits by screening breeding populations using the SNPs linked with the subunits of interest.