Comparison of T3SS clusters of eight sequenced strains of Xanthomonas . The organization of the hrp cluster encoding the T3SS and some T3-secreted proteins is compared using the R package GenoplotR for strains Xff 4834-R, Xac 306, Xcv 85–10, Xacm F1, Xcc ATCC33913, Xcr 756C, Xoo PXO99A, Xoc BLS256. Strains Xfa ICPB10535, Xcm NCPPB4381, Xg ATCC19865 and Xv ATCC35937 were not included as their hrp/hrc region is splitted on various contigs. Boxes of the same color indicate orthologous genes. Colinearity is represented by colored connectors. The hrp cluster is inserted in the vicinity of a tRNA-Arg gene, except for Xcc ATCC33913, X. campestris pv. raphani strain 756C (Xcr 756C), and X. oryzae pv. oryzae strain PXO99A (Xoo PXO99A). In strain Xoc BLS256, multiple insertions occurred between the ortholog of hpaF (aka xopAF) and the tRNA-Arg gene. These insertions in Xoc BLS256 carry virulence associated genes such as the T3E xopAD, TBDT, carbohydrate and salicylate esters degradation genes (sal operon).