STRUCTURE plot of the 379 rye accessions with K = 3 clusters based on 1054 DArT markers. The plot is sorted according to accession source and type. The order of accessions in the plot corresponds to the order of accessions in Additional file 1: Table S1. Each accession’s genome is represented by a single row, which is partitioned into colored segments in proportion to the estimated membership in the three subpopulations. Black line separates accessions of predefined groups.