Fig. 1

a Histogram summarizing the frequency of tolerant (0) vs susceptible (1) phenotypes in the panel of 85 accessions used for GWA analysis; b Genetic structure plot of the analyzed panel for the optimal number of a priori genetic clusters (K = 2 and K = 3), with ancestry proportion on the Y-axis. The red, yellow and light blue bars indicate the subpopulations I (breeding-derived), subpopulation II (Occidental non-breeding) and subpopulation III (Oriental origins), respectively; c PCA scatter plot of the first two principal component (PC1 and PC2) of the genetic relationship matrix for the analyzed panel. Red, yellow and light blue colours indicate the three subpopulation (I, II, III), respectively. The proportion of the explained variance is indicated in parenthesis; d Unrooted UPGMA tree showing the phylogenetic relationship among accessions. Black square indicate tolerant accessions. Red, yellow and light blue halos mark the assignment of each taxa to the respective subpopulations with a membership probability >0.8