Light-dependent Hypersensitive Response and Resistance Signaling Against Turnip Crinkle Virus in Arabidopsis

Plant J. 2006 Feb;45(3):320-34. doi: 10.1111/j.1365-313X.2005.02618.x.

Abstract

Resistance to Turnip Crinkle Virus (TCV) in Arabidopsis ecotype Dijon (Di)-17 is conferred by the resistance gene HRT and a recessive locus rrt. In Di-17, TCV elicits a hypersensitive response (HR), which is accompanied by increased expression of pathogenesis-related (PR) genes and high levels of salicylic acid (SA). We have previously shown that HRT-mediated resistance to TCV is dependent on SA-mediated signal transduction and that increased levels of SA confer enhanced resistance to TCV via upregulation of the HRT gene. Here we show that HRT-mediated HR and resistance are dependent on light. A dark treatment immediately following TCV inoculation suppressed HR, resistance and activation of the majority of the TCV-induced genes. However, the absence of light did not affect either TCV-induced elevated levels of free SA or the expression of HRT. Interestingly, in the dark, transgenic plants overexpressing HRT showed susceptibility, but overexpression of HRT coupled with high levels of endogenous SA resulted in pronounced resistance. Consistent with these results is the finding that exogenous application of SA prior to TCV inoculation partially overcame the requirement for light. Light was also required for N gene-mediated HR and resistance to Tobacco Mosaic Virus, suggesting that it is an important factor which may be generally required during defense signaling.

Publication types

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

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism
  • Arabidopsis / virology*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Arabidopsis Proteins / physiology
  • Carmovirus / pathogenicity*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Gene Expression Profiling
  • Gene Expression Regulation, Plant
  • Immunity, Innate
  • Light*
  • Models, Biological
  • Phenotype
  • Phytochrome A / physiology
  • Phytochrome B / physiology
  • Plant Leaves / anatomy & histology
  • Plant Leaves / metabolism
  • Plant Leaves / virology
  • Plants, Genetically Modified / drug effects
  • Plants, Genetically Modified / metabolism
  • Plants, Genetically Modified / virology
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism
  • Salicylic Acid / metabolism
  • Salicylic Acid / pharmacology
  • Signal Transduction
  • Tobacco Mosaic Virus / pathogenicity
  • Up-Regulation

Substances

  • Arabidopsis Proteins
  • DNA-Binding Proteins
  • HRT protein, Arabidopsis
  • PHYA protein, Arabidopsis
  • PHYB protein, Arabidopsis
  • Phytochrome A
  • Repressor Proteins
  • Phytochrome B
  • Salicylic Acid