The Identification of Quantitative Trait Loci for Sucrose and Stachyose Content in Soybean Seed.

Sucrose is a desirable sugar in soybean seed that affects the quality and taste of soyfoods, while stachyose is a non-digestible sugar that induces flatulence in non-ruminant animals. Therefore, soybean cultivars with high sucrose and/or low stachyose would be valuable for soyfood and meal markets. The objectives of this study were to identify quantitative trait loci (QTL) or genes associated with seed sucrose and stachyose content using simple sequence repeat (SSR) or single nucleotide polymorphism (SNP) markers. A low sucrose line, MFS-553, was crossed with a high sucrose plant introduction, PI 243545, to develop the sucrose QTL mapping population. A total of 97 SSR markers were used to screen the F_2:3 population and 2016 SNP markers were used to screen the F_3:4 population derived from MFS-553 x PI 243545. A normal stachyose cultivar, Osage, was crossed with a low stachyose line, V99-5089, to develop F₃ mapping population for genetic study of stachyose content. A total of 5 SSR and 16 SNP markers were used to screen the F_3:4 lines derived from Osage x V99-5089. For phenotyping the sugar profile, seed of F_2:3, F_3:5 and F_3:6 lines from MFS-553 x PI 243545 and seed of F_3:5 and F_3:6 lines from Osage x V99-5089 were analyzed for sucrose and stachyose using high performance liquid chromatography (HPLC). Composite interval mapping (CIM) in the MFS-553 x PI 243545 population revealed three QTL for seed sucrose on chromosome 5, 9, and 16, explaining 46%, 10% and 8% of phenotypic variation for sucrose content, respectively. CIM and Chi-square analysis in Osage x V99-5089 revealed two independent QTL/genes on chromosome 11 and 10, explaining 81% and 11% of phenotypic variation for stachyose content, respectively. These QTL can be used for marker assisted selection in breeding soybean lines with desired sugar profile.