Xanthomonas axonopodispv. citrumelo is a citrus pathogen causing citrus bacterial spot disease that is geographically restricted within the state of Florida. Illumina, 454 sequencing, and optical mapping were used to obtain a complete genome sequence ofX. axonopodispv. citrumelo strain F1, 4.9 Mb in size. The strain lacks plasmids, in contrast to other citrusXanthomonaspathogens. Phylogenetic analysis revealed that this pathogen is very close to the tomato bacterial spot pathogenX. campestrispv. vesicatoria 85-10, with a completely different host range. We also comparedX. axonopodispv. citrumelo to the genome of citrus canker pathogenX. axonopodispv. citri 306. Comparative genomic analysis showed differences in several gene clusters, like those for type III effectors, the type IV secretion system, lipopolysaccharide synthesis, and others. In addition topthA, effectors such asxopE3, xopAI, andhrpWwere absent fromX. axonopodispv. citrumelo while present inX. axonopodispv. citri. These effectors might be responsible for survival and the low virulence of this pathogen on citrus compared to that ofX. axonopodispv. citri. We also identified unique effectors inX. axonopodispv. citrumelo that may be related to the different host range as compared to that ofX. axonopodispv. citri.X. axonopodispv. citrumelo also lacks various genes, such assyrE1, syrE2, and RTX toxin family genes, which were present inX. axonopodispv. citri. These may be associated with the distinct virulences ofX. axonopodispv. citrumelo andX. axonopodispv. citri. Comparison of the complete genome sequence ofX. axonopodispv. citrumelo to those ofX. axonopodispv. citri andX. campestrispv. vesicatoria provides valuable insights into the mechanism of bacterial virulence and host specificity.
Prevalence, Host Range, and Comparative Genomic Analysis of Temperate Ochrobactrum Phages
