Damage mechanism of photosystem and light-dependent acquired thermotolerance of photosystem

高等植物的光系统II（PSII）对热胁迫非常敏感。光条件是决定热处理对PSII损伤的关键因素，即在黑暗中热处理对PSII损伤严重，而在光照下热处理对PSII损伤不明显。本研究分析了黑暗条件下的热损伤机制，以及光依赖的耐热性，在黑暗条件下，类囊体膜的过度还原可能通过产生活性氧（ROS）对PSII造成损伤。另一方面，光处理增强了PSII的耐热性，这种耐热性是通过促进PSI周围的循环电子流来支持的。

PhotosystemII (PSII) in higher plants is highly susceptible to heat stress. Light condition is a critical factor determining damage of PSII under heat condition, i.e. PSII is seriously damaged by heat treatment in the dark but not in the light. In this study, we analyzed heat-derived damage mechanism in the dark, and light-dependent thermotolerance.Under heat condition in the dark, over-reduction of thylakoid membrane causes damage of PSII through possible production of ROS. On the other hand, light treatment enhances thermotolerance of PSII, and the thermotolerance was supported by promoted cyclic electron flow around PSI.