Comparison of the genomes of two Xanthomonas pathogens with differing host specificities

Abstract

The genus Xanthomonas is a diverse and economically important group of bacterial phytopathogens, belonging to the gamma-subdivision of the Proteobacteria. Xanthomonas axonopodis pv. citri (Xac) causes citrus canker, which affects most commercial citrus cultivars, resulting in significant losses worldwide. Symptoms include canker lesions, leading to abscission of fruit and leaves and general tree decline. Xanthomonas campestris pv. campestris (Xcc) causes black rot, which affects crucifers such as Brassica and Arabidopsis. Symptoms include marginal leaf chlorosis and darkening of vascular tissue, accompanied by extensive wilting and necrosis. Xanthomonas campestris pv. campestris is grown commercially to produce the exopolysaccharide xanthan gum, which is used as a viscosifying and stabilizing agent in many industries. Here we report and compare the complete genome sequences of Xac and Xcc. Their distinct disease phenotypes and host ranges belie a high degree of similarity at the genomic level. More than 80% of genes are shared, and gene order is conserved along most of their respective chromosomes. We identified several groups of strain-specific genes, and on the basis of these groups we propose mechanisms that may explain the differing host specificities and pathogenic processes.

Phaeobacter gallaeciensis genomes from globally opposite locations reveal high similarity of adaptation to surface life

“…Several of the strain-specific genes have no homologs in any database ('orphan genes') and are interesting targets for further research, because they may account for P. gallaeciensis strain-specific metabolic traits and may also influence the host specificity (Mira, 2002;Silva et al, 2002). Our survey also suggests strain differentiation in the regulatory networks of extracytoplasmic function s factors and small RNAs (Supplementary Materials S12 and 13).…”

Identification of critical amino acid residues in the plague biofilm Hms proteins

“…Genes encoding orthologues of each of these Y. pestis proteins have been identified in a number of diverse organisms (Bell et al, 2004;da Silva et al, 2002;Jones et al, 1999;Lee et al, 2005;Paulsen et al, 2005;Salanoubat et al, 2002;Wang et al, 2004). Of these, the E. coli PgaABCD system is involved in formation of an EPS containing a b-1,6-N-acetyl-D-glucosamine polymer, and an EPS with a similar component is also part of the Y. pestis biofilm (Itoh et al, 2005;Wang et al, 2004).…”

Bacterial Genomes as New Gene Homes: The Genealogy of ORFans in E. coli

“…To identify those ORFs of E. coli MG1655 that are restricted to clades of different phylogenetic depths, we narrowed our analysis to the gene contents of sequenced enteric bacteria, currently the best represented bacterial group, including five strains of E. coli (Blattner et al 1997;Hayashi et al 2001;Perna et al 2001;Welch et al 2002;Wei et al 2003), two subspecies/serovars of S. enterica (McClelland et al 2001;Parkhill et al 2001a), two species of Buchnera (Shigenobu et al 2000;Tamas et al 2002), and two strains of Yersinia pestis (Parkhill et al 2001b;Deng et al 2002) as well as those of several other ␥-Proteobacteria, including Vibrio cholerae (Schoolnik and Yildiz 2000), Vibrio parahaemolyticus (Makino et al 2003), Haemophilus influenzae (Fleischmann et al 1995), Pasteurella multocida (May et al 2001), Pseudomonas aeruginosa (Stover et al 2000), Xylella fastidiosa (Simpson et al 2000), Xanthomonas campestris, and Xanthomonas citri (da Silva et al 2002). (Species are listed in order of increasing genetic distance to E.…”