Population structure of 91 soybean cultivars using 5107 SNP markers. a Estimation of the number of sub-populations. The left figure was a plot of ln (probability of data) vs. K ranging from 1 to 10 and the right figure was a plot of subpopulation number vs. delta K values. b Population structure of 91 soybean cultivars based on SNP markers. The x-axis indicates the cultivars, and the y-axis indicates the Q value from STRUCTURE 2.3.1. The red color represents one sub-group, the green color represents another. c PCA of 91 soybean cultivars with the top two principal components. d Neighbor-joining tree of the 91 soybean cultivars