Succinate dehydrogenase in Arabidopsis thaliana is regulated by light via phytochrome A

The effect of light on succinate dehydrogenase (SDH) activity and mRNA content was studied in Arabidopsis thaliana plants. The transition from darkness to light caused a short transient increase in the SDH activity followed by a decrease to a half of the original activity. The white or red light were found to be down-regulating factors for the mRNA content of the sdh1-2 and sdh2-3 genes and SDH catalytic activity both in A. thaliana wild-type plants and in the mutant deficient in the phytochrome B gene, but not in the mutant deficient in the phytochrome A gene, while the far-red light of 730 nm reversed the red light effect. It is concluded that phytochrome A participates in the regulation of mitochondrial respiration through effect on SDH expression.