Abstract
Plant mitochondria have alternative oxidase (AOX). AOX catalyzes the O2-depedent oxidation of ubiquinol, producing ubiquinone and water. AOX is not coupled to proton translocation and thus represents non-energy-conserving branch of the electron transport chain. It is suggested that AOX plays roles in preventing production of reactive oxygen species as well as in maintenance of the TCA cycle activity.
Arabidopsis thaliana has AOX1a-1d and AOX2, whose expression patterns differ among organs or stress treatments. Although it was demonstrated that AOX gene was induced and AOX protein was activated by stress treatments in suspension cells, it is not clear whether the expression and activation patterns of AOX correlate with its in vivo activity. In this study, we investigate the effects of expression and activation level of AOX on its in vivo activity, respiration and growth in A. thaliana plants under low-temperature or high-light stresses.
