Petiole angle is one of the important factors that affects the high-efficiency light posture of plants. It is very important to improve soybean plant architecture by adjusting the leaf angle petioles. Soybean petiole angle is a quantitative trait, which is limited to QTLs mapping for most studies up to date. The reported gene GmILPA1controlling leaf petiole angle gene was cloned from mutants. Identification of more regulatory genes and elite alleles is urgent both for the clarification of genetic mechanism for petiole angle and its breeding utilization. In this study, 783 and 690 soybean germplasms were phenotypic for petiole angle in Hainan and Beijing in 2019 and 2020, respectively, and genome-wide associated study (GWAS) were performed using genome-wide distributed SNPs. Results showed that the petiole angle at different nodes (top, middle, and bottom nodes) were in normal distribution, suggesting that the trait of typical quantitative was inheritance. A total of 325 SNPs associated with petiole angle were identified by two-point GWAS analysis in two years, including 51, 230, 10, and 34 SNPs for petiole angles of the top, middle, bottom, and mean value of different nodes, respectively. Three candidate genes (Glyma.05G059700: auxin regulatory protein, Glyma.06G076900: AFR, and Glyma.06G076000: COP9) were obtained by LD block analysis. Transcriptional analysis revealed that all these three candidate genes had high expression level in shoot apical meristem (SAM), however, high expression level were also identified in leaf for Glyma.06G076900, leaf and stem for Glyma.06G076000.
