Gac two-component system in Pseudomonas syringae pv. tabaci is required for virulence but not for hypersensitive reaction

Mizuri Marutani, Fumiko Taguchi, Yujiro Ogawa, Md Mijan Hossain, Yoshishige Inagaki, Kazuhiro Toyoda, Tomonori Shiraishi, Yuki Ichinose

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30 Citations (Scopus)


Pseudomonas syringae pv. tabaci 6605 causes wildfire disease on host tobacco plants. To investigate the regulatory mechanism of the expression of virulence, Gac two-component system-defective mutants, ΔgacA and ΔgacS, and a double mutant, ΔgacAΔgacS, were generated. These mutants produced smaller amounts of N-acyl homoserine lactones required for quorum sensing, had lost swarming motility, and had reduced expression of virulence-related hrp genes and the algT gene required for exopolysaccharide production. The ability of the mutants to cause disease symptoms in their host tobacco plant was remarkably reduced, while they retained the ability to induce hypersensitive reaction (HR) in the nonhost plants. These results indicated that the Gac two-component system of P. syringae pv. tabaci 6605 is indispensable for virulence on the host plant, but not for HR induction in the nonhost plants.

Original languageEnglish
Pages (from-to)313-322
Number of pages10
JournalMolecular Genetics and Genomics
Issue number4
Publication statusPublished - Apr 1 2008



  • GacA
  • GacS
  • Pseudomonas syringae pv. tabaci
  • Quorum sensing
  • Two-component system

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics

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