Genetic Association of Seed Yield with Component Traits in Glycine max under Different Water Regimes

Selecting soybean lines that can maintain high yields during drought is important to enhance the breeding of drought-tolerance strains of soybean. In this study, 200 BC1F4 lines and two parental lines were grown in 2011 and 2012 at Shanxi Agricultural University in China. Yield and its component characters were measured and analyzed under different water treatments. The results revealed that yield and its component characters value in drought stressed environments were lower than in non-stressed environments. Fifteen QTLs involved in nine traits were detected in the linkage groups G1-A1, G5-C1, G6-C21, G10-D2, G11-E, G14-G and G22-N. Large-effect loci were detected on near satt514 in the G10-D2 linkage group, Satt606 in the G11-E linkage group and Satt640 in the G6-C21 linkage group as in previous reports. The loci near satt514 in the G10-D2 linkage group were associated with majority of yield related traits under different water conditions. They are qPH-DS-D2-1, qPDN-DS-D2-1, qPNP-NS-D2-2, qPNP-DS-D2-1, qSP-NS-D2-1, qSP-DS-D2-1 and qSWP-DS-D2-1, respectively, in which the phenotypic contribution of qPDN-DS-D2-1, qPNP-DS-D2-1, qSP-DS-D2-1 and qSWP-DS-D2-1was more than 10.00%. Most loci associated with yield related traits are sensitive to water regimes. The additive and additive epistatic interaction effects (aa effects) was observed for controlling podding number of stem under drought stressed conditions and nine QTLs controlled yield related traits had additive and environment interaction effects (ae effects). Conditional QTL SWP-DS-D2-1 for SWP can be detected only by performing the phenotypic values of SWP conditioned on PDN, PNP or SP, indicating the expression of the QTL SWP-DS-D2-1 related to seed weight per plant was closely associated with variation in PDN, PNP and SP, which was consistent with the high correlation of DTI and yield related traits under DS. The results from this study facilitates the understanding of the genetic mechanism of the complex interactions among soybean major-effect drought-yield QTLs and molecular breeding for the improvement of soybean adaptability to drought in specific and/or broad regions. (c) 2018 Friends Science Publishers