Identification of genomic regions determining flower and pod numbers development in soybean (Glycine max L.)

Flower and pod numbers per plant are important agronomic traits underlying soybean yield. So far quantitative trait loci (QTL) detected for flower and pod-related traits have mainly focused on the final stage, and might therefore have ignored genetic effects expressed during a specific developmental stage. Here, dynamic expressions of QTL for flower and pod numbers were identified using 152 recombinant inbred lines (RILs) and a linkage map of 306 markers. Wide genetic variation was found among RILs; 17 unconditional and 18 conditional QTL were detected for the two traits at different developmental stages over two years. Some QTL were detected only at one stage and others across two or more stages, indicating that soybean flower and pod numbers development may be governed by time-dependent gene expression. Three main QTL (qfn-Chr18-2, qfn-Chr20-1, and qfn-Chr19) were detected for flower number, and two main QTL (qpn-Chr11 and qpn-Chr20) were detected for pod number. The phenotypic variation explained by them ranged from 6.1% to 34.7%. The markers linked to these QTL could be used in marker-assisted selection for increasing soybean flower and pod numbers, with the ultimate aim of increasing soybean yield. Comparison of the QTL regions for flower and pod numbers traits with the related genes reported previously showed that seven and four related genes were located in the QTL regions of qfn-Chr11 and qfn-Chr19, respectively. These results provide a basis for fine mapping and cloning of flower and pod development-related genes.