Abstract
Oxygenation of pheophorbide a is a key step in chlorophyll degradation, and it is catalyzed by pheophorbide a oxygenase (PaO). We previously reported that PaO was encoded by Accelerated cell death 1 gene, which was first identified as the mutant gene causing an enhanced cell death. Then antisense PaO transgenic Arabidopsis plants (As-ACD1) were analyzed to investigate the cell death induced by accumulation of pheophorbide a. Pheophorbide a was accumulated in As-ACD1 leaves during dark incubation because of the suppression of PaO expression. When dark-treated As-ACD1 were exposed to continuous light, the leaves of the mutant were bleached, probably due to the singlet oxygen generated by accumulated pheophorbide a. In addition, we found that dark-treated As-ACD1 leaves showed a cell death phenotype without re-illumination. The results indicated that pheophorbide a induced cell death in the light-independent manner. We will discuss the cell death induced by accumulation of pheophorbide a.
