title: The Pseudomonas viridiflava phylogroups in the P. syringae species complex are characterized by genetic variability and phenotypic plasticity of pathogenicity-related traits.
abstract: 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.
authors.affiliation: Department of Science and Technology for Agriculture, Forestry, Nature and Energy (DAFNE), Tuscia University, Viterbo, Italy; UR0407 Pathologie Végétale, INRA, Montfavet, France.
authors.forename: Claudia
authors.initials: C
authors.lastname: Bartoli
authors.forename: Odile
authors.initials: O
authors.lastname: Berge
authors.forename: Caroline L
authors.initials: CL
authors.lastname: Monteil
authors.forename: Caroline
authors.initials: C
authors.lastname: Guilbaud
authors.forename: Giorgio M
authors.initials: GM
authors.lastname: Balestra
authors.forename: Leonardo
authors.initials: L
authors.lastname: Varvaro
authors.forename: Corbin
authors.initials: C
authors.lastname: Jones
authors.forename: Jeffery L
authors.initials: JL
authors.lastname: Dangl
authors.forename: David A
authors.initials: DA
authors.lastname: Baltrus
authors.forename: David C
authors.initials: DC
authors.lastname: Sands
authors.forename: Cindy E
authors.initials: CE
authors.lastname: Morris
mesh_terms: D000220:Adaptation, Biological; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D058947:Bacterial Secretion Systems / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D056426:Genetic Loci; D014644:Genetic Variation; D016680:Genome, Bacterial; D044404:Genomic Islands; D005838:Genotype; D010641:Phenotype; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology; D011549:Pseudomonas / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D044224:Pseudomonas syringae / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D011198:Solanum tuberosum / Q000382:microbiology*; D014774:Virulence
chemical_list: C110610:AvrE protein, Pseudomonas syringae; D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems