Salicylic acid inhibits pathogen growth in plants through repression of the auxin signaling pathway

Curr Biol. 2007 Oct 23;17(20):1784-90. doi: 10.1016/j.cub.2007.09.025. Epub 2007 Oct 4.


The phytohormone auxin regulates almost every aspect of plant development. At the molecular level, auxin induces gene expression through direct physical interaction with the TIR1-like F box proteins, which in turn remove the Aux/IAA family of transcriptional repressors [1-4]. A growing body of evidence indicates that many plant pathogens can either produce auxin themselves or manipulate host auxin biosynthesis to interfere with the host's normal developmental processes [5-11]. In response, plants probably evolved mechanisms to repress auxin signaling during infection as a defense strategy. Plants overaccumulating the defense signal molecule salicylic acid (SA) frequently display morphological phenotypes that are reminiscent of auxin-deficient or auxin-insensitive mutants, indicating that SA might interfere with auxin responses. By using the Affymetrix ATH1 GeneChip for Arabidopsis thaliana, we performed a comprehensive study of the effects of SA on auxin signaling [12]. We found that SA causes global repression of auxin-related genes, including the TIR1 receptor gene, resulting in stabilization of the Aux/IAA repressor proteins and inhibition of auxin responses. We demonstrate that this inhibitory effect on auxin signaling is a part of the SA-mediated disease-resistance mechanism.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Arabidopsis / drug effects*
  • Arabidopsis / genetics
  • Arabidopsis / physiology*
  • Gene Expression Profiling
  • Genes, Plant / drug effects
  • Indoleacetic Acids / metabolism*
  • Mutation
  • Oligonucleotide Array Sequence Analysis
  • Plant Diseases / genetics
  • Plant Growth Regulators / physiology
  • Plants, Genetically Modified
  • Salicylic Acid / metabolism
  • Salicylic Acid / pharmacology*
  • Signal Transduction / drug effects
  • Thiadiazoles / pharmacology


  • Indoleacetic Acids
  • Plant Growth Regulators
  • Thiadiazoles
  • S-methyl benzo(1,2,3)thiadiazole-7-carbothioate
  • Salicylic Acid