Runaway cell death, but not basal disease resistance, in lsd1 is SA- and NIM1/NPR1-dependent

Plant J. 2002 Feb;29(3):381-91. doi: 10.1046/j.0960-7412.2001.01225.x.


LSD1 was defined as a negative regulator of plant cell death and basal disease resistance based on its null mutant phenotypes. We addressed the relationship between lsd1-mediated runaway cell death and signaling components required for systemic acquired resistance (SAR), namely salicylic acid (SA) accumulation and NIM1/NPR1. We present two important findings. First, SA accumulation and NIM1/NPR1 are required for lsd1-mediated runaway cell death following pathogen infection or application of chemicals that mimic SA action. This implies that lsd1-dependent cell death occurs 'downstream' of the accumulation of SA. As SA application triggers runaway cell death in lsd1 but not wild-type plants, we infer that LSD1 negatively regulates an SA-dependent signal leading to cell death. Thus SA is both a trigger and a required mediator of lsd1 runaway cell death. Second, neither SA accumulation nor NIM1/NPR1 function is required for the basal resistance operating in lsd1. Therefore LSD1 negatively regulates a basal defense pathway that can act upstream or independently of both NIM1/NPR1 function and SA accumulation following avirulent or virulent pathogen challenge. Our data, together with results from other studies, point to the existence of an SA-dependent 'signal potentiation loop' controlling HR. Continued escalation of signaling in the absence of LSD1 leads to runaway cell death. We propose that LSD1 is a key negative regulator of this signal potentiation.

Publication types

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

MeSH terms

  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Arabidopsis / drug effects
  • Arabidopsis / microbiology
  • Arabidopsis / physiology
  • Arabidopsis Proteins*
  • Cell Death / drug effects
  • Cell Death / physiology
  • DNA-Binding Proteins / drug effects
  • DNA-Binding Proteins / metabolism
  • Fungi / growth & development
  • Hydrogen Peroxide / metabolism
  • Immunity, Innate / drug effects
  • Oxidative Stress
  • Plant Leaves / drug effects
  • Plant Leaves / microbiology
  • Plant Leaves / physiology
  • Plant Proteins / metabolism*
  • Salicylic Acid / metabolism*
  • Salicylic Acid / pharmacology
  • Signal Transduction / drug effects
  • Transcription Factors / drug effects
  • Transcription Factors / metabolism


  • Arabidopsis Proteins
  • DNA-Binding Proteins
  • LSD1 protein, Arabidopsis
  • NPR1 protein, Arabidopsis
  • Plant Proteins
  • Transcription Factors
  • Hydrogen Peroxide
  • Salicylic Acid