Abstract
Mitochondrial respiratory system in illuminated leaves is closely associated with photosynthesis (e.g. redox-shuttling, photorespiration). The redox state of the respiratory chain during photosynthesis is likely to be dynamically modulated through such metabolic networks. Using HPLC, we established novel technique for the concurrent determination of plastoquinone (PQ) and ubiquinone (UQ) redox states. This method allowed us to know the in vivo redox states of PQ and UQ and to discuss the metabolic interaction between chloroplasts and mitochondria in a quantitative context. We demonstrate the in vivo PQ and UQ redox states, with regard to the differences among several plant species and the transient responses during the induction phase of photosynthesis. We also present the effects of the deficiency of mitochondrial alternative oxidase, a unique terminal oxidase in plant mitochondria, in Arabidopsis thaliana.
