Loss of non-host resistance of Arabidopsis NahG to Pseudomonas syringae pv. phaseolicola is due to degradation products of salicylic acid

Plant J. 2003 Feb;33(4):733-42. doi: 10.1046/j.1365-313x.2003.01665.x.


In plants carrying the NahG transgene, salicylate hydroxylase converts salicylic acid (SA) to catechol. Arabidopsis NahG plants are defective in non-host resistance to Pseudomonas syringae pv. phaseolicola strain 3121 (Psp), suggesting that resistance requires SA signaling. However, several mutants with defects in SA signaling, including eds1, pad4, eds5, sid2, and npr1, remain resistant to Psp, demonstrating that susceptibility of NahG plants is not due to absence of SA. SA synthesis is blocked in sid2NahG double mutants, but resistance to Psp is retained. Therefore, it must be the degradative action of NAHG on SA that causes the loss of resistance of NahG to Psp. Treatment of plants with catechol compromised Psp resistance suggesting that the effect of NahG on resistance results from catechol production. Application of catalase to NahG or catechol-treated wild-type plants partially restored resistance to Psp, suggesting that the deleterious effect of catechol results from inappropriate production of hydrogen peroxide. These results indicate that conclusions about SA requirements based solely on phenotypes of NahG plants should be re-evaluated.

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis / metabolism
  • Arabidopsis / microbiology
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Carboxylic Ester Hydrolases / genetics
  • Carboxylic Ester Hydrolases / metabolism
  • Catalase / pharmacology
  • Catechols / pharmacology
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Immunity, Innate / drug effects
  • Immunity, Innate / genetics
  • Immunity, Innate / physiology
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism
  • Mixed Function Oxygenases / genetics
  • Mixed Function Oxygenases / metabolism*
  • Mutation
  • Plant Diseases / genetics
  • Plant Diseases / microbiology
  • Protein Kinases / genetics
  • Protein Kinases / metabolism
  • Pseudomonas / growth & development*
  • Salicylic Acid / metabolism*
  • Schizosaccharomyces pombe Proteins*
  • Signal Transduction / genetics
  • Signal Transduction / physiology
  • Transgenes / genetics


  • Arabidopsis Proteins
  • Catechols
  • DNA-Binding Proteins
  • EDS1 protein, Arabidopsis
  • EDS5 protein, Arabidopsis
  • Membrane Transport Proteins
  • NPR1 protein, Arabidopsis
  • Schizosaccharomyces pombe Proteins
  • Mixed Function Oxygenases
  • Catalase
  • salicylate 1-monooxygenase
  • Protein Kinases
  • Sid2 protein, S pombe
  • Carboxylic Ester Hydrolases
  • PAD4 protein, Arabidopsis
  • catechol
  • Salicylic Acid