Virulence systems of Pseudomonas syringae pv. tomato promote bacterial speck disease in tomato by targeting the jasmonate signaling pathway

Youfu Zhao, Roger Thilmony, Carol L. Bender, Andreas Schaller, Sheng Yang He, Gregg A. Howe

Research output: Contribution to journalArticle

Abstract

Pseudomonas syringae pv. tomato strain DC3000 (Pst DC3000) causes bacterial speck disease on tomato. The pathogenicity of Pst DC3000 depends on both the type III secretion system that delivers virulence effector proteins into host cells and the phytotoxin coronatine (COR), which is thought to mimic the action of the plant hormone jasmonic acid (JA). We found that a JA-insensitive mutant (jai1) of tomato was unresponsive to COR and highly resistant to Pst DC3000, whereas host genotypes that are defective in JA biosynthesis were as susceptible to Pst DC3000 as wild-type (WT) plants. Treatment of WT plants with exogenous methyl-JA (MeJA) complemented the virulence defect of a bacterial mutant deficient in COR production, but not a mutant defective in the type III secretion system. Analysis of host gene expression using cDNA microarrays revealed that COR works through Jai1 to induce the massive expression of JA and wound response genes that have been implicated in defense against herbivores. Concomitant with the induction of JA and wound response genes, the type III secretion system and COR repressed the expression of pathogenesis-related (PR) genes in Pst DC3000-infected WT plants. Resistance of jail plants to Pst DC3000 was correlated with a high level of PR gene expression and reduced expression of JA/wound response genes. These results indicate that COR promotes bacterial virulence by activating the host's JA signaling pathway, and further suggest that the type III secretion system might also modify host defense by targeting the JA signaling pathway in susceptible tomato plants.

Original languageEnglish (US)
Pages (from-to)485-499
Number of pages15
JournalPlant Journal
Volume36
Issue number4
DOIs
StatePublished - Nov 1 2003
Externally publishedYes

Keywords

  • Bacterial speck disease
  • Coronatine
  • Jasmonic acid
  • Pseudomonas syringae
  • Salicylic acid
  • Type III secretion

ASJC Scopus subject areas

  • Genetics
  • Plant Science
  • Cell Biology

Fingerprint Dive into the research topics of 'Virulence systems of Pseudomonas syringae pv. tomato promote bacterial speck disease in tomato by targeting the jasmonate signaling pathway'. Together they form a unique fingerprint.

  • Cite this