The plant pathogen Pseudomonas syringae pv. tomato is genetically monomorphic and under strong selection to evade tomato immunity.

Autor: Rongman Cai, James Lewis, Shuangchun Yan, Haijie Liu, Christopher R Clarke, Francesco Campanile, Nalvo F Almeida, David J Studholme, Magdalen Lindeberg, David Schneider, Massimo Zaccardelli, Joao C Setubal, Nadia P Morales-Lizcano, Adriana Bernal, Gitta Coaker, Christy Baker, Carol L Bender, Scotland Leman, Boris A Vinatzer
Jazyk: angličtina
Rok vydání: 2011
Předmět:
Zdroj: PLoS Pathogens, Vol 7, Iss 8, p e1002130 (2011)
Druh dokumentu: article
ISSN: 1553-7366
1553-7374
DOI: 10.1371/journal.ppat.1002130
Popis: Recently, genome sequencing of many isolates of genetically monomorphic bacterial human pathogens has given new insights into pathogen microevolution and phylogeography. Here, we report a genome-based micro-evolutionary study of a bacterial plant pathogen, Pseudomonas syringae pv. tomato. Only 267 mutations were identified between five sequenced isolates in 3,543,009 nt of analyzed genome sequence, which suggests a recent evolutionary origin of this pathogen. Further analysis with genome-derived markers of 89 world-wide isolates showed that several genotypes exist in North America and in Europe indicating frequent pathogen movement between these world regions. Genome-derived markers and molecular analyses of key pathogen loci important for virulence and motility both suggest ongoing adaptation to the tomato host. A mutational hotspot was found in the type III-secreted effector gene hopM1. These mutations abolish the cell death triggering activity of the full-length protein indicating strong selection for loss of function of this effector, which was previously considered a virulence factor. Two non-synonymous mutations in the flagellin-encoding gene fliC allowed identifying a new microbe associated molecular pattern (MAMP) in a region distinct from the known MAMP flg22. Interestingly, the ancestral allele of this MAMP induces a stronger tomato immune response than the derived alleles. The ancestral allele has largely disappeared from today's Pto populations suggesting that flagellin-triggered immunity limits pathogen fitness even in highly virulent pathogens. An additional non-synonymous mutation was identified in flg22 in South American isolates. Therefore, MAMPs are more variable than expected differing even between otherwise almost identical isolates of the same pathogen strain.
Databáze: Directory of Open Access Journals
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