Free radicals mediate systemic acquired resistance

Cell Rep. 2014 Apr 24;7(2):348-355. doi: 10.1016/j.celrep.2014.03.032. Epub 2014 Apr 13.


Systemic acquired resistance (SAR) is a form of resistance that protects plants against a broad spectrum of secondary infections. However, exploiting SAR for the protection of agriculturally important plants warrants a thorough investigation of the mutual interrelationships among the various signals that mediate SAR. Here, we show that nitric oxide (NO) and reactive oxygen species (ROS) serve as inducers of SAR in a concentration-dependent manner. Thus, genetic mutations that either inhibit NO/ROS production or increase NO accumulation (e.g., a mutation in S-nitrosoglutathione reductase [GSNOR]) abrogate SAR. Different ROS function additively to generate the fatty-acid-derived azelaic acid (AzA), which in turn induces production of the SAR inducer glycerol-3-phosphate (G3P). Notably, this NO/ROS→AzA→G3P-induced signaling functions in parallel with salicylic acid-derived signaling. We propose that the parallel operation of NO/ROS and SA pathways facilitates coordinated regulation in order to ensure optimal induction of SAR.

Publication types

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

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / immunology*
  • Arabidopsis / metabolism
  • Arabidopsis / microbiology
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Dicarboxylic Acids / metabolism
  • Glutathione Reductase / genetics
  • Glutathione Reductase / metabolism
  • Glycerophosphates / metabolism
  • Nitric Oxide / metabolism*
  • Nitric Oxide Synthase / genetics
  • Nitric Oxide Synthase / metabolism
  • Plant Immunity*
  • Pseudomonas syringae / pathogenicity
  • Reactive Oxygen Species / metabolism*


  • Arabidopsis Proteins
  • Dicarboxylic Acids
  • Glycerophosphates
  • Reactive Oxygen Species
  • Nitric Oxide
  • alpha-glycerophosphoric acid
  • NOA1 protein, Arabidopsis
  • Nitric Oxide Synthase
  • Glutathione Reductase
  • S-nitrosoglutathione reductase, Arabidopsis
  • azelaic acid