QTL Mapping and Interaction Analysis of Seed Protein Content and Oil Content in Soybean

【Objective】 Quantitative trait loci associated with protein and oil contents were identified and epistatic interactions in soybean. The results will offer a clue for quality gene mining and molecular breeding in soybean. 【Method】 Total 147 recombination inbred lines(RIL) were derived from a cross of Charleston and Dongnong 594, the F2:19-F2:20 generation of RIL was used as experimental materials. Using CIM and MIM model method by Windows QTL Cartographer V.2.5, QTL associated with protein and oil contents were identified. The epistatic effect and environmental effect between QTLs were analyzed by QTL Network 2.1. 【Result】 Under six planting environments including Harbin, Hongxinglong, Jiamusi, and Mudanjiang in 2011 and 2012, a total of nine QTLs for protein content and eleven QTLs for oil content were mapped. Protein content QTLs were mapped on six linkage groups A1, C2, D1a, G, H, and O. The QTLs explained 5.3%-18.6% of phenotypic variation, the maximum rate of qPro-H-1 on linkage group H was 18.6%, the minimum rate of qPro-D1a-2 on linkage group D1a was 5.3%. Five protein content QTLs in single planting environment were simultaneously detected by two methods, which were qPro-O-1, qPro-A1-1, qPro-D1a-1, qPro-D1a-2, and qPro-C2-2. Oil content QTL were mapped on eight groups A1, A2, B1, C2, D1a, E, L, and M. The QTLs explained 7.1%-24.4% of phenotypic variation, the maximum rate of qOil-B1-2 on linkage group B1 was 24.4%, the minimum rate of qOil-C2-3 on linkage group C2 was 7.1%. Two oil content QTLs qOil-C2-1, qOil-M-1 were detected in single planting environment. Besides, two oil content QTLs were detected in over 2 environments, qOil-A1-1 was indentified in 2011 in Harbin and in 2011 in Hongxinglong two planting environments, qOil-B1-2 was indentified in 2011 in Hongxinglong, in 2011 in Mudanjiang and in 2012 in Harbin three planting environments. A total of three pairs protein epistatic effect QTL and four pairs oil content epistatic QTL were found. Protein epistatic effect was 0.2068-0.3124, the QTLs explained 0.0227%-0.0265% of phenotypic variation, were mapping on linkage groups A1, C2, D1, and E, qPro-A1-3 and qPro-C2-1 were negative interaction effect, others were positive interaction effect. Both two epistatic effect QTLs on linkage groups A1 and D1a. Oil epistatic effect was between 0.0926 and 0.1682, the QTLs explained 0.0294%-0.0754% of phenotypic variation, and the QTLs were mapping on linkage groups A1, C2, I, J, N and O. qOil-C2-4 and qOil-N-1 had negative interaction effect, and the other 3 loci had positive interaction effect to phenotype. Interactions were identified between qOil-N-1 with qOil-C2-1 and qOil-N-1 with qOil-C2-4, respectively. Six pairs of QE interaction effects QTLs were detected, qPro-D1a-3 and qPro-E-1 pairs were not detected in Jiamusi in 2012. 【Conclusion】 In total, nine QTLs related to protein content and eleven QTLs related to oil content were mapped. Three QTL pairs with epistatic effects for protein content and four QTL pairs with epistatic effects for oil content were detected, respectively.