Syntenic relationships among crucifer species of QTL regions containing genes encoding NBS-LRR proteins. Black bars represent the chromosomal blocks and white regions are N-gaps. Red and blue indicate genes for which orthologous genes were found in relative species, with those encoding NBS-LRR genes in red and non-NBS-LRR genes in blue. Green denotes genes that were annotated only in one species; Bo-Brassica oleracea, Br-Brassica rapa, and At-Arabidopsis thaliana. (a) Syntenic regions that include disease resistance genes (b) Syntenic regions with different numbers of NBS-LRR-encoding genes clustered in B. oleracea and B. rapa.