title: Host plant-dependent phenotypic reversion of Ralstonia solanacearum from non-pathogenic to pathogenic forms via alterations in the phcA gene.
abstract: Ralstonia solanacearum is a plant pathogenic bacterium that undergoes a spontaneous phenotypic conversion (PC) from a wild-type pathogenic to a non-pathogenic form. PC is often associated with mutations in phcA, which is a key virulence regulatory gene. Until now, reversion to the wild-type pathogenic form has not been observed for PC variants and the biological significance of PC has been questioned. In this study, we characterized various alterations in phcA (eight IS element insertions, three tandem duplications, seven deletions and a base substitution) in 19 PC mutants from the model strain GMI1000. In five of these variants, reversion to the pathogenic form was observed in planta, while no reversion was ever noticed in vitro whatever culture media used. However, reversion was observed for a 64 bp tandem duplication in vitro in the presence of tomato root exudate. This is the first report showing a complete cycle of phenotypic conversion/reversion in a plant pathogenic bacterium.
authors.affiliation: Institut des Interactions Plantes-Microorganismes, INRA-CNRS, BP27, 31326, Castanet-Tolosan, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Poussier
authors.forename: Philippe
authors.initials: P
authors.lastname: Thoquet
authors.forename: Danièle
authors.initials: D
authors.lastname: Trigalet-Demery
authors.forename: Séverine
authors.initials: S
authors.lastname: Barthet
authors.forename: Damien
authors.initials: D
authors.lastname: Meyer
authors.forename: Matthieu
authors.initials: M
authors.lastname: Arlat
authors.forename: André
authors.initials: A
authors.lastname: Trigalet
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D018551:Solanum lycopersicum / Q000378:metabolism / Q000382:microbiology; D009154:Mutation; D010641:Phenotype; D010935:Plant Diseases / Q000382:microbiology; D043368:Ralstonia solanacearum / Q000235:genetics* / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C082933:PhcA protein, Ralstonia solanacearum; D014157:Transcription Factors