Identification of QTL and genes for pod number in soybean by linkage analysis and genome-wide association studies

Pod number is an important component of yield in soybean (Glycine max(L.) Merr.), and pods are unevenly distributed in the upper, middle and lower parts of the plant. Here, linkage analysis combined with genome-wide association study (GWAS) was used to identify 20 pod number-related traits in four-way recombinant inbred lines (FW-RILs) derived from crosses between the four soybean varieties (Kenfeng 14 x Kenfeng 15) x (Heinong 48 x Kenfeng 19). The results show that pod number-related traits are highly influenced by genetic factors, while the environment plays only a minor role. A total of 602 QTLs were identified, of which 52 were detected in multiple environments (over two environments). In addition, GWAS detected 26 common QTNs (identified by multiple methods or environments) in the QTL intervals. Based on gene ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, 11 potential candidate genes were identified that likely involved the growth and development of soybean pods. These findings will help elucidate the genetic basis of pod number traits.