Genetic Mapping of QTL Associated with Seed Macronutrients Accumulation in ‘MD 96-5722’ by ‘Spencer’ Recombinant In­bred Lines of Soybean

Research of quantitative trait loci (QTL) for macronutrient ac­cumulation in soybean seed is limited. Therefore, the objec­tive of this research was to identify QTL related to macronutri­ents (N, C, S, P, K, Ca, and Mg) in seeds in 92 F5:7 recombinant inbred lines (RILs) developed from a cross between MD 96-5722 (MD) and Spencer using a total 5,376 Single Nucleotide Polymorphism (SNP) markers. A genetic linkage map based on SNP markers was constructed using the Illumina Infinium SoySNP6K BeadChip Array. The RILs were genotyped using 537 polymorphic, reliably segregating SNP markers. A total of 8 QTL for K (qPOT001-qPOT008) were identified on LGs D1b (Chr 1), N (Chr 3), A1 (Chr 5), O (Chr 10), F (Chr 13), B2 (Chr 14), and J (Chr 16). Four QTL for Mg (qMAG001-qMAG004) were identified on LGs N (Chr 3), A1 (Chr 5), J (Chr 16), and G (Chr 18). One QTL for P (qPHO001), one for C on LG J (Chr 16), one for N (qNIT001) and S (qSUL001) on the same LG J (Chr 16), and one QTL for Ca (qCAL001) on LG G (Chr 18). K and Mg QTL were clustered together on LG A1 (Chr 5) with a peak position of 9.50 cM and LOD support interval of 8.50-9.50 cM. Similar observation was noticed for P, K, Mg, C, N, and S, where the QTL were clustered on LG J (Chr 16) with peak position of 11 cM for K, P, and S, and 10 cM for C and N, and 12 cM for Mg. The LOD support inter­vals for all these clustered QTL were between 8.90 and 12.30 cM. The QTL clustering of these nutrients suggests possible common physiological and genetic relationships, suggest­ing possible similar metabolic processes and pathways for these nutrients. The inverse relationships between N:S ratio and all nutrients suggest possible use of N:S ratio as a mea­sure for higher nutrients accumulation in seed. Since most of QTL identified in this study were not previously reported, this research will further help breeders to improve nutrient ac­cumulation in seeds and contribute to our understanding of the physiological and genetic bases of seed nutrition quality.