Identification of quantitative trait loci underlying soybean ( Glycine max [L.] Merr .) seed weight including main, epistatic and QTL × environment effects in different regions of Northeast China

Seed weight (SW) is the important soybean (Glycine max [L.] Merr.), yield component and also affected the quality of soybean-derived foods. The aim of this study was to identify the quantitative trait loci (QTL) underlying SW through 112 recombinant inbred lines (RILs) derived from the cross between Zhongdou27 (G.max, designated by its bigger seed size, 21.9g/100 seeds) and Jiunong 20 (G.max, smaller seed size, 17.5g/100 seeds). Phenotypic data were collected from this RIL population after it was grown in the sixteen tested environments. A total of eight QTL (QSW1-1, QSW2-1, QSW2-2, QSW5-1, QSW15-1, QSW17-1, QSW19-1 and QSW20-1) were identified, and they could explain 4.23%-14.65% of the phenotypic variation. Among these eight QTL, three QTL (QSW1-1 located on the interval of Sat_159-Satt603 of chromosome (Chr) 1 (LGD1a), QSW19-1 located on the interval of Sat_340-Satt523 of Chr 19 (LGL) and QSW20-1 located on Sat_418-Sat_105 of Chr 20 (LGI)) were newly identified and could explain 4.235%-10.08%, 8.45%-13.49% and 8.08%-10.18% of the phenotypic variation, respectively. Six of the eight identified QTL including QSW2-2, QSW5-1, QSW15-1, QSW17-1, QSW19-1 and QSW20-1 exhibited a significant additive (a) effect, while two QTL (QSW2-1 and QSW19-1) only displayed significant additive-by-environment (ae) effects. A total of four epistatic pairwise QTL for SW were identified in the different environments. These eight QTL and their genetic information obtained here were valuable for molecular marker-assisted selection and the realization of a reasonable SW breeding programme in soybean.