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

Abstract

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.