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A Draft Genome Sequence of Pseudomonas syringae pv. tomato T1 Reveals a Type III Effector Repertoire Significantly Divergent from That of Pseudomonas syringae pv. tomato DC3000

January 2009 , Volume 22 , Number  1
Pages  52 - 62

Nalvo F. Almeida,1,7 Shuangchun Yan,2 Magdalen Lindeberg,3 David J. Studholme,4 David J. Schneider,5 Bradford Condon,3 Haijie Liu,2 Carlos J. Viana,7 Andrew Warren,1 Clive Evans,1 Eric Kemen,4 Dan MacLean,4 Aurelie Angot,3,6 Gregory B. Martin,3,6 Jonathan D. Jones,4 Alan Collmer,3 Joao C. Setubal,1,8 and Boris A. Vinatzer2

1Virginia Bioinformatics Institute, Virginia Tech, Blacksburg, VA 24061, U.S.A.; 2Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Latham Hall, Ag Quad Lane, Blacksburg, VA 24061, U.S.A.; 3Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, U.S.A. 4Sainsbury Laboratory, Norwich NR4 7UH, U.K.; 5U. S. Department of Agriculture Agricultural Research Service, Ithaca, NY 14853, U.S.A.; 6Boyce Thompson Institute for Plant Research, Ithaca, NY 14853, U.S.A.; 7Department of Computing and Statistics, Federal University of Mato Grosso do Sul, Brazil; 8Department of Computer Science, Virginia Tech, Blacksburg, VA 24061, U.S.A.

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Accepted 10 September 2008.

Diverse gene products including phytotoxins, pathogen-associated molecular patterns, and type III secreted effectors influence interactions between Pseudomonas syringae strains and plants, with additional yet uncharacterized factors likely contributing as well. Of particular interest are those interactions governing pathogen-host specificity. Comparative genomics of closely related pathogens with different host specificity represents an excellent approach for identification of genes contributing to host-range determination. A draft genome sequence of Pseudomonas syringae pv. tomato T1, which is pathogenic on tomato but nonpathogenic on Arabidopsis thaliana, was obtained for this purpose and compared with the genome of the closely related A. thaliana and tomato model pathogen P. syringae pv. tomato DC3000. Although the overall genetic content of each of the two genomes appears to be highly similar, the repertoire of effectors was found to diverge significantly. Several P. syringae pv. tomato T1 effectors absent from strain 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 P. syringae pv. tomato T1, suggesting that other effectors and possibly type III secretion system--independent factors also play a role in this interaction.

Additional keywords:effector-triggered immunity, nonhost resistance, pyrosequencing, Solexa sequencing.

© 2009 The American Phytopathological Society