Activation of an EDS1-mediated R-gene pathway in the snc1 mutant leads to constitutive, NPR1-independent pathogen resistance

Mol Plant Microbe Interact. 2001 Oct;14(10):1131-9. doi: 10.1094/MPMI.2001.14.10.1131.


The Arabidopsis NPR1 protein is an essential regulatory component of systemic acquired resistance (SAR). Mutations in the NPR1 gene completely block the induction of SAR by signals such as salicylic acid (SA). An Arabidopsis mutant, snc1 (suppressor of npr1-1, constitutive 1), was isolated in a screen for suppressors of npr1-1. In the npr1-1 background, the snc1 mutation resulted in constitutive resistance to Pseudomonas syringae maculicola ES4326 and Peronospora parasitica Noco2. High levels of SA were detected in the mutant and shown to be required for manifestation of the snc1 phenotype. The snc1 mutation was mapped to the RPP5 resistance (R) gene cluster and the eds1 mutation that blocks RPP5-mediated resistance suppressed snc1. These data suggest that a RPP5-related resistance pathway is activated constitutively in snc1. This pathway does not employ NPR1 but requires the signal molecule SA and the function of EDS1. Moreover, in snc1, constitutive resistance is conferred in the absence of cell death, which is often associated with R-gene mediated resistance.

Publication types

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

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism
  • Arabidopsis / microbiology
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Chromosome Mapping
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / metabolism
  • Epistasis, Genetic
  • Fungal Proteins / genetics*
  • Fungal Proteins / metabolism
  • Gene Expression
  • Immunity, Innate
  • Membrane Proteins*
  • Mutation
  • Oomycetes / genetics
  • Oomycetes / pathogenicity
  • Plant Diseases / genetics
  • Plant Diseases / microbiology
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Pseudomonas / genetics
  • Pseudomonas / pathogenicity
  • R-SNARE Proteins
  • Saccharomyces cerevisiae Proteins*
  • Salicylic Acid / metabolism
  • Signal Transduction*


  • Arabidopsis Proteins
  • DNA-Binding Proteins
  • EDS1 protein, Arabidopsis
  • Fungal Proteins
  • Membrane Proteins
  • NPR1 protein, Arabidopsis
  • Plant Proteins
  • R-SNARE Proteins
  • RPP5 protein, Arabidopsis
  • SNC1 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Salicylic Acid