The siderophore pyoverdine of Pseudomonas syringae pv. tabaci 6605 is an intrinsic virulence factor in host tobacco infection

Fumiko Taguchi, Tomoko Suzuki, Yoshishige Inagaki, Kazuhiro Toyoda, Tomonori Shiraishi, Yuki Ichinose

Research output: Contribution to journalArticlepeer-review

96 Citations (Scopus)


To investigate the role of iron uptake mediated by the siderophore pyoverdine in the virulence of the plant pathogen Pseudomonas syringae pv. tabaci 6605, three predicted pyoverdine synthesis-related genes, pvdJ, pvdL, and fpvA, were mutated. The pvdJ, pvdL, and fpvA genes encode the pyoverdine side chain peptide synthetase III L-Thr-L-Ser component, the pyoverdine chromophore synthetase, and the TonB-dependent ferripyoverdine receptor, respectively. The ΔpvdJ and ΔpvdL mutants were unable to produce pyoverdine in mineral salts-glucose medium, which was used for the iron-depleted condition. Furthermore, the ΔpvdJ and ΔpvdL mutants showed lower abilities to produce tabtoxin, extracellular polysaccharide, and acyl homoserine lactones (AHLs), which are quorum-sensing molecules, and consequently had reduced virulence on host tobacco plants. In contrast, all of the mutants had accelerated swarming ability and increased biosurfactant production, suggesting that swarming motility and biosurfactant production might be negatively controlled by pyoverdine. Scanning electron micrographs of the surfaces of tobacco leaves inoculated with the mutant strains revealed only small amounts of extracellular polymeric matrix around these mutants, indicating disruption of the mature biofilm. Tolerance to antibiotics was drastically increased for the ΔpvdL mutant, as for the ΔpsyI mutant, which is defective in AHL production. These results demonstrated that pyoverdine synthesis and the quorum-sensing system of Pseudomonas syringae pv. tabaci 6605 are indispensable for virulence in host tobacco infection and that AHL may negatively regulate tolerance to antibiotics.

Original languageEnglish
Pages (from-to)117-126
Number of pages10
JournalJournal of bacteriology
Issue number1
Publication statusPublished - Jan 2010

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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