Overexpression of ALTERNATIVE OXIDASE1a alleviates mitochondria-dependent programmed cell death induced by aluminium phytotoxicity in Arabidopsis

J Exp Bot. 2014 Aug;65(15):4465-78. doi: 10.1093/jxb/eru222. Epub 2014 May 26.

Abstract

Alternative oxidase (AOX) is a terminal oxidase found in all plants, and functions to maintain the electron flux and reduce the production of reactive oxygen species (ROS). Our previous study demonstrated that aluminium (Al) treatment could induce increased expression of the AOX1a gene, but the mechanism of how AOX1a participates in the regulation of Al-induced programmed cell death (PCD) is still not clear. To investigate the possible mechanism, mitochondrial ROS production and the behaviour of mitochondria, as well as caspase-3-like activation were monitored under Al treatment in wild-type (WT), AOX1a-lacking (aox1a), and AOX1a-overexpressing (AOX1a-OE) Arabidopsis. Our results showed that Al treatment increased the expression of AOX1a at both the transcriptional and translational levels. Overexpression of AOX1a reduced mitochondrial ROS production by maintaining the mitochondrial electron flux, and alleviated subsequent mitochondrial dysfunction and caspase-3-like activation in Al-induced PCD. Moreover, it was found that a change in AOX1a level could influence the expression levels of downstream functional genes that play protective roles in Al-induced PCD. Experiments using mutants and inhibitors demonstrated that superoxide anion (O2 (-)) derived from mitochondria was involved in Al-induced upregulation of AOX1a gene expression. Taken together, these results indicated that overexpression of AOX1a alleviated Al-induced PCD by maintaining mitochondrial function and promoting the expression of protective functional genes, providing new insights into the signalling cascades that modulate the Al phytotoxicity mechanism.

Keywords: Alternative oxidase; Arabidopsis; aluminium phytotoxicity; caspase-3-like; mitochondrial respiratory chain; programmed cell death; reactive oxygen species..

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aluminum / toxicity*
  • Arabidopsis / drug effects*
  • Arabidopsis / enzymology*
  • Caspase 3 / metabolism
  • Cell Death / drug effects
  • Cell Respiration / drug effects
  • Electron Transport
  • Gene Expression Regulation, Plant
  • Membrane Potentials / drug effects
  • Mitochondria / drug effects*
  • Mitochondrial Proteins / metabolism*
  • Oxidoreductases / metabolism*
  • Plant Proteins / metabolism*
  • Reactive Oxygen Species / metabolism

Substances

  • Mitochondrial Proteins
  • Plant Proteins
  • Reactive Oxygen Species
  • Aluminum
  • Oxidoreductases
  • alternative oxidase
  • Caspase 3