QTLs and epistasis for drought-tolerant physiological index in soybean (Glycine max L.) across different environments

The additive and epistatic effects and their genotype x environment (GE) effects on percentage gain with physiological traits under different environments were analyzed in soybean. The genetic characters of physiological traits in soybean and characters of quantitative trait loci (QTL) detected in different environments are discussed. A backcross inbred line (BIL) population of soybean derived from the cross of strong drought tolerant wild soybean, SNWS0048 as a recipient parent and drought-sensitive variety Jinda73 as a donor parent was examined to identify the QTL and epistatic QTL and GE effects on drought-tolerant physiological traits in Shanxi, China, in 2008 and 2010. Six QTLs with additive (a) effects and/or additive x environment interaction (ae) effects and three pairs of QTLs with additive x epistatic main (aa) and/or epistasis x environment interaction (aae) effects were detected in different water environment over two years. Six QTLs with a effects and/or ae effects were mapped to linkage groups D2, G, M and N. Among them, there were two QTLs without ae effects, one with ae effects in all four environments, two QTLs with ae effects in two environments and one QTL with ae effects in only one environment. Among three pairs of QTLs, one pair was identified with aa effect and aae effect, one pair only exhibited aa effect, and one pair only had aae effect without aa effect. These indicated that different water environments could affect the expression of genes relevant to drought tolerant traits.