Influence of chloroplastic photo-oxidative stress on mitochondrial alternative oxidase capacity and respiratory properties: a case study with Arabidopsis yellow variegated 2

Plant Cell Physiol. 2008 Apr;49(4):592-603. doi: 10.1093/pcp/pcn031. Epub 2008 Feb 21.


Mitochondrial alternative oxidase (AOX), the unique respiratory terminal oxidase in plants, catalyzes the energy-wasteful cyanide (CN)-resistant respiration. Although it has been demonstrated that leaf AOX is up-regulated under high-light (HL) conditions, the in vivo mechanism of AOX up-regulation by light is still unknown. In the present study, we examined whether the photo-oxidative stress in the chloroplast modulates mitochondrial respiratory properties, especially the AOX capacity, using Arabidopsis leaf-variegated mutant yellow variegated 2 (var2) and exposing plants to HL. var2 mutants lack FtsH2 metalloprotease required for the repair of damaged PSII. Indeed, var2-1 suffered from photo-oxidative stress even before the HL treatments. While the activities of tricarboxylic acid cycle enzymes and cytochrome c oxidase in var2-1 were almost identical to those in the wild type, the amount of AOX protein and the CN-resistant respiration rate were higher in var2-1. Real-time PCR analysis revealed that HL treatment induced the expression of some energy-dissipating respiratory genes, including AOX1a, NDB2 and UCP5, more strongly in var2-1. Western blotting using var2-1 leaf extracts specific to green or white sectors, containing functional or non-functional photosynthetic apparatus, respectively, revealed that more AOX protein was induced in the green sectors by the HL treatment. These results indicate that photo-oxidative stress by excess light is involved in the regulation of respiratory gene expression and the modulation of respiratory properties, especially the AOX up-regulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Dependent Proteases / metabolism*
  • Arabidopsis / cytology*
  • Arabidopsis / enzymology
  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / metabolism*
  • Cell Respiration / drug effects
  • Cell Respiration / radiation effects
  • Chlorophyll / metabolism
  • Chloroplasts / drug effects
  • Chloroplasts / enzymology
  • Chloroplasts / metabolism*
  • Chloroplasts / radiation effects
  • Electron Transport / drug effects
  • Electron Transport / radiation effects
  • Fluorescence
  • Gene Expression Regulation, Plant / drug effects
  • Gene Expression Regulation, Plant / radiation effects
  • Genes, Plant
  • Hydrogen Peroxide / pharmacology
  • Light*
  • Lipid Peroxidation / drug effects
  • Lipid Peroxidation / radiation effects
  • Malate Dehydrogenase (NADP+) / metabolism
  • Membrane Proteins / metabolism*
  • Mitochondria / drug effects
  • Mitochondria / enzymology*
  • Mitochondria / radiation effects
  • Mitochondrial Proteins
  • Mutation / genetics
  • Oxidative Stress / drug effects
  • Oxidative Stress / radiation effects
  • Oxidoreductases / metabolism*
  • Phenotype
  • Photosynthesis / drug effects
  • Photosynthesis / radiation effects
  • Plant Leaves / drug effects
  • Plant Leaves / enzymology
  • Plant Leaves / radiation effects
  • Plant Proteins


  • Arabidopsis Proteins
  • Membrane Proteins
  • Mitochondrial Proteins
  • Plant Proteins
  • Chlorophyll
  • Hydrogen Peroxide
  • Oxidoreductases
  • alternative oxidase
  • Malate Dehydrogenase (NADP+)
  • ATP-Dependent Proteases
  • VAR2 protein, Arabidopsis