|Wechter, William - Pat|
Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2013
Publication Date: 3/29/2013
Citation: Sarris, P.F., Trantas, E.A., Baltras, D.A., Bull, C.T., Wechter, W.P., Yan, S., Ververidis, F., Almeida, N.F., Jones, C.D., Dangl, J.L., Panopoulos, N.J., Vinatzer, B.A., Goumas, D.E. 2013. Comparative genomics of multiple strains of Pseudomonas cannabina pv. alisalensis, a potential model pathogen of both Monocots and Dicots. PLoS One. 8(3):1-16. Interpretive Summary: Cruciferous vegetables are an important part of a healthy diet. The pathogens studied here, are responsible for significant economic loss and can limit the supply of healthy vegetables for consumers. In addition to causing disease on crucifers they have the ability to also cause disease on grasses. Comparing the DNA sequences of bacteria like these, with broad ranges of hosts, to bacteria with a restricted host range will help identify genes and systems involved in determining host range and virulence Using this approach this research identified: 1) genes that may be useful for designing specific detection and quantification methods key in early detection and treatment of the disease; 2) differences in genes involved in virulence that could be the target of disease control approaches and that could be important to understand the adaptation to a broad range of hosts; and 3) novel hypothesis. Further research will test the hypotheses generated and deploy the information for disease management.
Technical Abstract: Comparative genomics of closely related pathogens that differ in host range can provide insights into mechanisms of host-pathogen interactions and host adaptation. Sequencing multiple strains of the same pathogen further reveals information concerning pathogen diversity and the molecular basis of virulence. Here we present a comparative analysis of draft genome sequences for four strains of Pseudomonas cannabina pathovar alisalensis (Pcal), one of the causative agents of bacterial blight of crucifers, isolated from geographically distant areas of Greece and the USA. Since Pcal causes disease on a range of plant species, including monocots and dicots, these draft genome sequences provide a foundation for understanding host range evolution across a variety of host species. Like other phytopathogenic Pseudomonads, Pcal strains harbour a hrp/hrc gene cluster that codes for a type III secretion system. Surprisingly, phylogenetic analysis based on the hrp/hrc cluster genes/proteins, suggests localized recombination with P. syringae and suggests functional divergence within the hrp/hrc cluster. Despite significant conservation of overall genetic content across Pcal genomes, comparison of type III effector repertoires reinforce previous molecular data suggesting the existence of two distinct lineages within this pathovar. Furthermore, all Pcal strains analyzed, harbor two distinct genomic islands predicted to code for type VI secretion systems (T6SSs). While, one of these systems isorthologous to known P. syringae T6SSs, the other more closely resembles a T6SS found within P. aeruginosa. In summary, our study provides the basis to unravel Pcal adaptation to both monocots and dicots and the involved pathogenic mechanisms.