title: Synthesis of redox-active molecules and their signaling functions during the expression of plant disease resistance.
abstract: CONCLUSIONS
  Activation of immune responses in plants is associated with a parallel burst of both reactive oxygen intermediates (ROIs) and nitric oxide (NO). The mechanisms by which these small redox-active molecules are synthesized and their signaling functions are critical for plants to defend themselves against pathogen infection.
  
  
  BACKGROUND
  The synthesis of apoplastic ROIs by plants after pathogen recognition has long been attributed to membrane-bound NAPDH oxidases. However, the emerging data suggest a role for other enzymes in various subcellular locations in ROI production after defense activation. It is becoming widely appreciated that NO exerts its biochemical function through the S-nitrosylation of reactive cysteine thiols on target proteins, constituting a key post-translational modification. Recent evidence suggests that S-nitrosylation of specific defense-related proteins regulates their activity.
  
  
  RESULTS
  The source(s) of NO production after pathogen recognition remain(s) poorly understood. Some NO synthesis can be attributed to the activity of nitrate reductase but to date, no nitric oxide synthase (NOS) has been identified in higher plants. However, the signaling functions of S-nitrosylation are becoming more apparent and thus dissecting the molecular machinery underpinning this redox-based modification is vital to further our understanding of plant disease resistance.
  
  
  CONCLUSIONS
  In addition to identifying new contributors to the oxidative burst, the discovery of an NOS in higher plants would significantly move the field forward. Since S-nitrosylation has now been confirmed to play various roles in immune signaling, this redox-based modification is a potential target to exploit for improving disease resistance in crop species.
authors.affiliation: Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Skelly
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Loake
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000378:metabolism; D060467:Disease Resistance; D018506:Gene Expression Regulation, Plant; D019255:NADPH Oxidases / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D010084:Oxidation-Reduction; D010935:Plant Diseases / Q000209:etiology* / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D010944:Plants / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D010940:Plant Proteins; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D000445:Aldehyde Oxidoreductases; C087006:formaldehyde dehydrogenase, glutathione-independent; D019255:NADPH Oxidases