Interplay between JA, SA and ABA signalling during basal and induced resistance against Pseudomonas syringae and Alternaria brassicicola

Victor Flors, Jurriaan Ton, Ronald Van Doorn, Gabor Jakab, Pilar García-Agustín, Brigitte Mauch-Mani

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Abstract

We have examined the role of the callose synthase PMR4 in basal resistance and β-aminobutyric acid-induced resistance (BABA-IR) of Arabidopsis thaliana against the hemi-biotrophic pathogen Pseudomonas syringae and the necrotrophic pathogen Alternaria brassicicola. Compared to wild-type plants, the pmr4-1 mutant displayed enhanced basal resistance against P. syringae, which correlated with constitutive expression of the PR-1 gene. Treating the pmr4-1 mutant with BABA boosted the already elevated levels of PR-1 gene expression, and further increased the level of resistance. Hence, BABA-IR against P. syringae does not require PMR4-derived callose. Conversely, pmr4-1 plants showed enhanced susceptibility to A. brassicicola, and failed to show BABA-IR. Wild-type plants showing BABA-IR against A. brassicicola produced increased levels of JA. The pmr4-1 mutant produced less JA upon A. brassicicola infection than the wild-type. Blocking SA accumulation in pmr4-1 restored basal resistance, but not BABA-IR against A. brassicicola. This suggests that the mutant's enhanced susceptibility to A. brassicicola is caused by SA-mediated suppression of JA, whereas the lack of BABA-IR is caused by its inability to produce callose. A. brassicicola infection suppressed ABA accumulation. Pre-treatment with BABA antagonized this ABA accumulation, and concurrently potentiated expression of the ABA-responsive ABI1 gene. Hence, BABA prevents pathogen-induced suppression of ABA accumulation, and sensitizes the tissue to ABA, causing augmented deposition of PMR4-derived callose.

Original languageEnglish
Pages (from-to)81-92
Number of pages12
JournalPlant Journal
Volume54
Issue number1
DOIs
Publication statusPublished - Apr 1 2008

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Keywords

  • ABA
  • BABA
  • Callose
  • Induced resistance
  • JA
  • PMR4

ASJC Scopus subject areas

  • Genetics
  • Plant Science
  • Cell Biology

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