The Structure and phylogeny of the LPS cluster. A) Schematic comparison of LPS gene clusters described in the present study. Genes conserved in different strains are given identical color. Genes specific to individual strains are given unique color. "Hpo pro" indicates an ORF encoding for a hypothetical protein. The red color-coded genes in Xp genes are absent in any of the sequenced xanthomonads. B) Phylogenetic tree based on conserved metB and etfA genes that flank the variable LPS locus. Strains abbreviations are as in the main text. Arrow indicates the horizontal gene transfer event in the lineage that gave rise to Xp.