The structure analysis divided our population into five groups, which was validated by the principal components analysis (PCA) and cluster analysis.

<p>(A) Population structure analysis of 217 sub-core entries showing five sub-groups, the estimated membership probability listed on the y-axis and each entry represented by a thin vertical line in different color: red = ARO, <i>aromatic</i>; blue = AUS, <i>aus</i>; pink = IND, <i>indica</i>; green = TEJ, <i>temperate japonica</i> and yellow = TRJ, <i>tropical japonica</i>. (B) The spatial distribution of the entries with two dimensions in the principal components analysis (PCA). (C) The unweighted pair-group method with arithmetic mean (UPGMA) tree based on Nei's genetic distance using five sub-group partitioning.