叶绿体活性氧参入了3－AIPTA引起的拟南芥叶片坏死过程

3-AIPTA (3-acetyl-5-isopropyltetramic acid), a derivate of tetramic acid, can cause a brown leaf spot disease in many plants and may quickly kill seedlings of mono- and dicotyledonous plants. In this study, to further elucidate the mode of action of 3-AIPTA, a series of experiments was performed to assess the production and role of reactive oxygen species (ROS) during 3-AIPTA-induced cell necrosis. When Arabidopsis leaves were incubated with 3-AIPTA, the PSII electron transport beyond QA and the reduction of end acceptors at the PSI acceptor side were inhibited, followed by the occurrence of charge recombination and electron leakage to O2, resulting in the chloroplast-derived oxidative burst. However, the main antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) lost their activity. Excess ROS molecules directly attacked a variety of cellular components and subsequently caused electrolyte leakage, lipid peroxidation and cell membrane disruption. Finally, this led to cell destruction and leaf tissue necrosis. Thus, 3-AIPTA-triggered leaf necrosis of Arabidopsis is a result of direct oxidative injury from the chloroplast-originated ROS burst attributed to the inhibition of photosynthetic electron transport.