QTL mapping for the number of branches and pods using wild chromosome segment substitution lines in soybean [<i>Glycine max</i> (L.) Merr.]

Abstract

Annual wild soybean characterized with more number of branches and pods may contain favourable exotic genes/alleles for improving the yield potential of cultivated soybeans. To evaluate the wild alleles/segments, the chromosome segment substitution line population SojaCSSLP3 comprising 158 lines with N24852 (wild) as the donor and NN1138-2 (cultivated) as the recurrent parent was tested under three environments. The phenotypic data along with 198 simple sequence repeat markers were analysed for qualitative trait loci (QTL)/segments associated with the number of branches on the main stem (BN) and number of pods per plant (PN) using the inclusive composite interval mapping procedure (RSTEP-LRT-ADD model) of ICIM version 3.0. The analysis was carried out for individual environments due to a significant G × E interaction. A total of eight QTL/segments associated with BN and eight QTL/segments associated with PN were detected under the three environments, with all the wild segments having positive effects. Among these, two QTL/segments for each of the two traits could be detected under two or three environments and three QTL/segments could be detected for both traits. Four QTL/segments associated with BN and one QTL/segment associated with PN were identified only in SojaCSSLP3 , not reported for cultivated crosses in the literature. The detected wild segments may provide materials for further characterization, cloning and pyramiding of the alleles conferring the two traits.