Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/10/2008
Publication Date: 1/1/2009
Citation: Almeida, N.F., Yan, S., Lindeberg, M., Studholme, D., Schneider, D.J., Condon, B., Liu, H., Viana, C.J., Warren, A., Evans, C., Kemen, E., Maclean, D., Angot, A., Martin, G.B., Jones, J.D., Collmer, A., Setubal, J.C., Vinatzer, B.A. 2009. A draft genome sequence of Pseudomonas syringae pv. tomato strain T1 reveals a repertoire of type III related genes significantly divergent from that of Pseudomonas syringae pv tomato strain DC3000 . Molecular Plant-Microbe Interactions. 22(1):52-62. Interpretive Summary: Closely related strains of bacterial plant pathogens may have different host ranges (species of susceptible plants) and there has been much speculation about the nature of the genetic basis for these differences. The genetic basis of host range differences between two well-studied strains of Pseudomonas syringae, both of which cause disease in tomato is the focus of this study. These two strains, P. syringae pv. tomato T1 and P. syringae pv. tomato DC3000 differ in their ability to cause disease on Arabidopsis thaliana. The genome sequence of P. syringae pv. tomato T1 was obtained and compared to the previously published sequence P. syringae pv. tomato DC3000. These genome comparisons revealed important differences in the list of proteins secreted by a key virulence pathway, the type III secretion system. These differences account for some, but not all, of the observed differences in host range.
Technical Abstract: Comparative genomics of pathogens with different host specificity can be used to identify genes related to host range determination. A draft genome sequence of Pseudomonas syringae pv. tomato (Pto) T1, non-pathogenic on Arabidopsis thaliana, was obtained for this purpose and compared to the genome of the closely related A. thaliana and tomato model pathogen P. syringae pv. tomato DC3000. Although the overall genetic content of the two genomes appears to be highly similar, the repertoire of effectors was found to diverge significantly. Several Pto T1 effectors absent from Pto DC3000 were confirmed to be translocated into plants, with the well-studied effector AvrRpt2 representing a likely candidate for host range determination. However, the presence of avrRpt2 was not found sufficient to explain A. thaliana resistance to Pto T1 suggesting that other effectors and possibly T3S independent factors also play a role in this interaction.