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Nonagricultural reservoirs contribute to emergence and evolution of Pseudomonas syringae crop pathogens
Author(s) -
Monteil Caroline L.,
Cai Rongman,
Liu Haijie,
Mechan Llontop Marco E.,
Leman Scotland,
Studholme David J.,
Morris Cindy E.,
Vinatzer Boris A.
Publication year - 2013
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12316
Subject(s) - pseudomonas syringae , biology , virulence , population , crop , host (biology) , pathogen , effector , susceptible individual , phylogenetics , range (aeronautics) , ecology , gene , genetics , demography , materials science , sociology , composite material , microbiology and biotechnology
Summary While the existence of environmental reservoirs of human pathogens is well established, less is known about the role of nonagricultural environments in emergence, evolution, and spread of crop pathogens. Here, we analyzed phylogeny, virulence genes, host range, and aggressiveness of Pseudomonas syringae strains closely related to the tomato pathogen P. syringae pv. tomato ( Pto ), including strains isolated from snowpack and streams. The population of Pto relatives in nonagricultural environments was estimated to be large and its diversity to be higher than that of the population of Pto and its relatives on crops. Ancestors of environmental strains, Pto , and other genetically monomorphic crop pathogens were inferred to have frequently recombined, suggesting an epidemic population structure for P. syringae . Some environmental strains have repertoires of type III ‐secreted effectors very similar to Pto , are almost as aggressive on tomato as Pto , but have a wider host range than typical Pto strains. We conclude that crop pathogens may have evolved through a small number of evolutionary events from a population of less aggressive ancestors with a wider host range present in nonagricultural environments.