Identification of Quantitative Trait Loci Associated with Seed Quality Traits in Two Early-Maturing Soybean Populations

In Canada, soybean ( Glycine max (L.) Merr.) is primarily cultivated in three provinces (Ontario, Quebec, and Manitoba). Canadian breeders want to expand the current cultivation range to more northern agro-environments by developing early-maturing elite lines while maintaining good seed quality traits. To examine quantitative trait loci involved in 100-seed weight and seed protein, oil, and fatty acid (oleic, linolenic, and linoleic acids) contents, we generated an early-maturing recombinant inbred line population (QS15544 RIL ) and an F 2 :F 3 (QS15524 F2:F3 ) population adapted to cultivation zones MGs 00 and 000, and phenotyped them for 3 years and 1 year, respectively. Using two mapping algorithms (Inclusive composite interval mapping and Genome-wide composite interval mapping), we identified a total of 12 major regions that were either associated with QS15544 RIL (five loci), QS15524 F2:F3 (four loci), or both (three loci) populations. Of the 12 identified regions, three (RIL_GM12, RIL_GM16, and F2_GM04.2) were not previously identified and might, respectively, serve as novel sources of regulation for oil content, seed weight, and oleic acid. For the RIL_GM05 locus, we identified two novel variants in Glyma.05G244100/ MOTHER OF FT AND TFL1, a gene with a confirmed role in the regulation of oleic and linoleic acid contents. Two of the major loci (RIL_GM04 and RIL_GM16) associated with the 100-seed weight trait and one locus (F2_GM04.2) associated with oleic acid were found to be overlapping three loci ( E8-r1, GM16:5,680,173–5,730,237, and E8-r2) involved in early-maturity and/or shorter pod-filling that were previously identified by our group, suggesting possible breeding bottlenecks due to linkage drag or pleiotropic effects.