期刊
PLANT AND CELL PHYSIOLOGY
卷 50, 期 4, 页码 719-729出版社
OXFORD UNIV PRESS
DOI: 10.1093/pcp/pcp035
关键词
Arabidopsis; Cell death; Pheophorbide a; Senescence
资金
- Ministry of Education, Culture, Sports, Science and Technology of Japan [17GS0314, 68700307]
- Grants-in-Aid for Scientific Research [17GS0314] Funding Source: KAKEN
Tetrapyrroles are well-known photosensitizers. In plants, various intermediate molecules of tetrapyrrole metabolism have been reported to induce cell death in a light-dependent manner. In contrast to these reports, we found that pheophorbide a, a key intermediate of chlorophyll catabolism, causes cell death in complete darkness in a transgenic Arabidopsis plant, As-ACD1. In this plant, expression of mRNA for pheophorbide a oxygenase was suppressed by expression of Acd1 antisense RNA; thus, As-ACD1 accumulated an excessive amount of pheophorbide a when chlorophyll breakdown occurred. We observed that when senescence was induced by a continuous dark period, leaves of As-ACD1 plants became dehydrated. By measuring electrolyte leakage, we estimated that 50 of the leaf cells underwent cell death within a 5d period of darkness. Light and electron microscopic observations indicated that the cellular structure had collapsed in a large population of cells. Partially covering a leaf with aluminum foil resulted in light-independent cell death in the covered region and induced bleaching in the uncovered regions. These results indicate that accumulation of pheophorbide a induces cell death under both darkness and illumination, but the mechanisms of cell death under these conditions may differ. We discuss the possible mechanism of light-independent cell death and the involvement of pheophorbide a in the signaling pathway for programmed cell death.
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