Comparison of the genome structures of B. rapa and A. thaliana based on 24 ancestral karyotype genome building blocks. The genome structure of At was based on the reports of Schranz et al.  and Lysak et al. . The position of genome blocks in the Br chromosome was defined by a comparison of Br-At syntenic relationships and the At-AK mapping results. Br sequences were connected to form continuous sequences. Block boundaries, orientation, and gaps between syntenic blocks are shown in Additional data file 4. Each color corresponds to a syntenic region between genomes. The Br genome is triplicated and more thoroughly rearranged than the At genome.