Host plant-dependent phenotypic reversion of Ralstonia solanacearum from non-pathogenic to pathogenic forms via alterations in the phcA gene.
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.
Poussier
Stéphane
S
Institut des Interactions Plantes-Microorganismes, INRA-CNRS, BP27, 31326, Castanet-Tolosan, France.
Thoquet
Philippe
P
Trigalet-Demery
Danièle
D
Barthet
Séverine
S
Meyer
Damien
D
Arlat
Matthieu
M
Trigalet
André
A
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
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C082933:PhcA protein, Ralstonia solanacearum; D014157:Transcription Factors