Free radical-mediated systemic immunity in plants

Curr Opin Plant Biol. 2014 Aug;20:127-34. doi: 10.1016/j.pbi.2014.05.012. Epub 2014 Jun 12.


Systemic acquired resistance (SAR) is a form of defense that protects plants against a broad-spectrum of secondary infections by related or unrelated pathogens. SAR related research has witnessed considerable progress in recent years and a number of chemical signals and proteins contributing to SAR have been identified. All of these diverse constituents share their requirement for the phytohormone salicylic acid, an essential downstream component of the SAR pathway. However, recent work demonstrating the essential parallel functioning of nitric oxide (NO)-derived and reactive oxygen species (ROS)-derived signaling together with SA provides important new insights in the overlapping pathways leading to SAR. This review discusses the potential significance of branched pathways and the relative contributions of NO/ROS-derived and SA-derived pathways in SAR.

Publication types

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

MeSH terms

  • Free Radicals / metabolism*
  • Nitric Oxide / metabolism
  • Plant Growth Regulators / metabolism
  • Plant Immunity*
  • Plants / immunology*
  • Plants / metabolism
  • Reactive Oxygen Species / metabolism
  • Salicylic Acid / metabolism
  • Signal Transduction*


  • Free Radicals
  • Plant Growth Regulators
  • Reactive Oxygen Species
  • Nitric Oxide
  • Salicylic Acid