QTL associated with seed protein and oil concentration from three sources of high protein in soybeans

Breeding for high protein and oil in soybeans [Glycine max (L.) Merr.] is difficult due to the lack of variability for both traits in adapted germplasm and negative correlation between protein and oil and yield. Protein and oil quantitative trait loci (QTL) have been found in exotic germplasm but additional QTL that do not confer opposite effects for both traits need to be identified. The objectives of this study were to identify QTL associated with seed protein and oil concentration in three populations with different sources of high protein, PI 82278,HHP and L69-183. Each source were crossed to the cultivar Williams and high protein F4 lines were selected. The selected lines were crossed to Williams 82, a backcrossed derived line from Williams with the Rps sub 1 sup k allele for Phytophthora rot resistance, and high protein F5 lines were selected. The selected lines were backcrossed to Williams 82 and individual F2 plants were harvested to create 120 random BC2 F2:3 lines from each donor parent. The lines plus the parents were evaluated for oil and protein in two replications at three locations for two years in Illinois, USA. Simple sequence repeats were used to genotype the F2 derived lines. QTL analysis using composite interval mapping detected 15 QTL for protein and oil across three populations. All but one protein QTL were inherited from the exotic parents while all oil QTL was derived from Williams 82. A QTL for protein and oil associated with Satt 239 was common among the three populations but some QTL were population specific. Although most protein QTL were associated with low oil, QTL on linkage group (LG) 1 from PI 82278 and on LG D1a from L69-183 increased protein with no effect on oil. Results of this study underscore the potential of exotic germplasm for improving seed quality traits in soybeans.