Abstract
Soybean meal is the main protein source for animal feed, but it has low content of the essential amino acids cysteine (Cys) and methionine (Met). In this research, an exotic germplasm (PI 399000) was crossed with ‘Woodruff’ to develop an F5-derived recombinant inbred line (RIL) population for mapping quantitative trait loci for seed composition. The population was grown in six environments, and protein, oil, Cys, and Met were determined with near-infrared spectroscopy. RILs were genotyped with the SoySNP6K BeadChip, and 1865 SNPs were used for analysis. QTL analysis identified three loci on chromosomes (Chrs) 6, 15 and 17 in at least five environments for protein; two QTLs on Chrs 14 and 17 in all environments for oil; three QTLs on Chrs 3, 6 and 10 for Cys and Met in at least three environments; and two QTLs for seed size on Chrs 17 and 20 in all environments. Stacking of protein and Cys + Met QTLs can increase both traits simultaneously, and 13 breeding lines were identified with improved seed composition. The markers linked to the QTLs can be used to assist the development of cultivars with improved meal quality.