Arabidopsis GH3-LIKE DEFENSE GENE 1 is required for accumulation of salicylic acid, activation of defense responses and resistance to Pseudomonas syringae

Guru Jagadeeswaran, Surabhi Raina, Biswa R. Acharya, Shahina B. Maqbool, Stephen L. Mosher, Heidi M. Appel, Jack C. Schultz, Daniel F. Klessig, Ramesh Raina

Research output: Contribution to journalArticle

87 Scopus citations

Abstract

In Arabidopsis, the GH3-like gene family consists of 19 members, several of which have been shown to adenylate the plant hormones jasmonic acid, indole acetic acid and salicylic acid (SA). In some cases, this adenylation has been shown to catalyze hormone conjugation to amino acids. Here we report molecular characterization of the GH3-LIKE DEFENSE GENE 1 (GDG1), a member of the GH3-like gene family, and show that GDG1 is an important component of SA-mediated defense against the bacterial pathogen Pseudomonas syringae. Expression of GDG1 is induced earlier and to a higher level in response to avirulent pathogens compared to virulent pathogens. gdg1 null mutants are compromised in several pathogen defense responses, including activation of defense genes and resistance against virulent and avirulent bacterial pathogens. Accumulation of free and glucoside-conjugated SA (SAG) in response to pathogen infection is compromised in gdg1 mutants. All defense-related phenotypes of gdg1 can be rescued by external application of SA, suggesting that gdg1 mutants are defective in the SA-mediated defense pathway(s) and that GDG1 functions upstream of SA. Our results suggest that GDG1 contributes to both basal and resistance gene-mediated inducible defenses against P. syringae (and possibly other pathogens) by playing a critical role in regulating the levels of pathogen-inducible SA. GDG1 is allelic to the PBS3 (avrPphB susceptible) gene.

Original languageEnglish (US)
Pages (from-to)234-246
Number of pages13
JournalPlant Journal
Volume51
Issue number2
DOIs
StatePublished - Jul 1 2007

Keywords

  • Arabidopsis
  • Bacterial pathogen
  • Defense signaling
  • GDG1
  • GH3-LIKE DEFENSE GENE 1
  • Salicylic acid

ASJC Scopus subject areas

  • Genetics
  • Plant Science
  • Cell Biology

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