ATP synthesis inhibitors as well as respiratory inhibitors increase steady-state level of alternative oxidase mRNA in Arabidopsis thaliana

The oxygen uptake in mitochondria can be uncoupled from ATP synthesis by th e product of a single gene, the alternative oxidase (AOX) gene, which may b e involved in signal transduction from mitochondria to the nucleus. To bett er understand induction of this gene in higher plants, we investigated the effects of the cytochrome respiratory inhibitors and ATP synthesis inhibito rs on the expression of the AOXs of Arabidopsis thaliana. A Northern blot a nalysis showed the AOX1a transcripts were increased by treatment of antimyc in A and myxothiazol, which act on complex III of the respiratory chain, an d by NaN3, which acts on complex IV. AOX1a mRNA was also strongly induced b y oligomycin (F1F0-ATP synthase inhibitor) and weakly induced by 2,4-DNP (A TP synthesis uncoupler) at the maximum dose. These results indicate that no t only inhibition of electron transfer but also inhibition of ATP synthesis in mitochondria induces the transcription of AOX1a.