Pseudomonas viridiflava phylogroups in the P. syringae species complex are characterized by genetic variability and phenotypic plasticity of pathogenicity‐related traits

• Published in: Environmental microbiology 2014-07, Vol.16 (7), p.2301-2315
• Main Authors: Bartoli, Claudia, Berge, Odile, Monteil, Caroline L, Guilbaud, Caroline, Balestra, Giorgio M, Varvaro, Leonardo, Jones, Corbin, Dangl, Jeffery L, Baltrus, David A, Sands, David C, Morris, Cindy E
• Format: Article
• Language: English
• Subjects: Adaptation, Biological; Agricultural sciences; Animal, plant and microbial ecology; aquatic habitat; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacterial Secretion Systems - genetics; Bacteriology; Biodiversity and Ecology; Biological and medical sciences; Environmental Sciences; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial; General aspects; genes; Genetic Loci; Genetic Variation; Genome, Bacterial; Genomic Islands; genomics; Genotype; Life Sciences; loci; Microbial ecology; Microbiology; Miscellaneous; pathogenicity; pathogenicity islands; Phenotype; phenotypic plasticity; Phylogeny; Plant Diseases - microbiology; potatoes; Pseudomonas - classification; Pseudomonas - genetics; Pseudomonas - metabolism; Pseudomonas - pathogenicity; Pseudomonas syringae; Pseudomonas syringae - genetics; Pseudomonas syringae - metabolism; Pseudomonas syringae - pathogenicity; Pseudomonas viridiflava; saprophytes; Solanum tuberosum; Solanum tuberosum - microbiology; Type III secretion system; Virulence
• ISSN: 1462-2912; 1462-2920
• DOI: 10.1111/1462-2920.12433

As a species complex, Pseudomonas syringae exists in both agriculture and natural aquatic habitats. P. viridiflava, a member of this complex, has been reported to be phenotypically largely homogenous. We characterized strains from different habitats, selected based on their genetic similarity to previously described P. viridiflava strains. We revealed two distinct phylogroups and two different kinds of variability in phenotypic traits and genomic content. The strains exhibited phase variation in phenotypes including pathogenicity and soft rot on potato. We showed that the presence of two configurations of the Type III Secretion System [single (S‐PAI) and tripartite (T‐PAI) pathogenicity islands] are not correlated with pathogenicity or with the capacity to induce soft rot in contrast to previous reports. The presence/absence of the avrE effector gene was the only trait we found to be correlated with pathogenicity of P. viridiflava. Other Type III secretion effector genes were not correlated with pathogenicity. A genomic region resembling an exchangeable effector locus (EEL) was found in S‐PAI strains, and a probable recombination between the two PAIs is described. The ensemble of the variability observed in these phylogroups of P. syringae likely contributes to their adaptability to alternating opportunities for pathogenicity or saprophytic survival.