Journal Article

Influence of Chloroplastic Photo-Oxidative Stress on Mitochondrial Alternative Oxidase Capacity and Respiratory Properties: A Case Study with Arabidopsis <i>yellow variegated 2</i>

Keisuke Yoshida, Chihiro Watanabe, Yusuke Kato, Wataru Sakamoto and Ko Noguchi

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 49, issue 4, pages 592-603
Published in print April 2008 | ISSN: 0032-0781
Published online April 2008 | e-ISSN: 1471-9053 | DOI: https://dx.doi.org/10.1093/pcp/pcn031
Influence of Chloroplastic Photo-Oxidative Stress on Mitochondrial Alternative Oxidase Capacity and Respiratory Properties: A Case Study with Arabidopsis yellow variegated 2

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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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.

Keywords: Alternative oxidase; Arabidopsis thaliana; Energy-dissipating respiration; Photo-oxidative stress; yellow variegated 2

Journal Article.  6750 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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