Department of Biology, University of Turku, SF-20500, Turku, Finland.
Photosynth Res. 1990 Nov;26(2):109-17. doi: 10.1007/BF00047082.
High light treatments were given to attached leaves of pumpkin (Cucurbita pepo L.) at room temperature and at 1°C where the diffusion- and enzyme-dependent repair processes of Photosystem II are at a minimum. After treatments, electron transfer activities and fluorescence induction were measured from thylakoids isolated from the treated leaves. When the photoinhibition treatment was given at 1°C, the Photosystem II electron transfer assays that were designed to require electron transfer to the plastoquinone pool showed greater inhibition than electron transfer from H2O to paraphenyl-benzoquinone, which measures all PS II centers. When the light treatment was given at room temperature, electron transfer from H2O to paraphenyl-benzoquinone was inhibited more than whole-chain electron transfer. Variable fluorescence measured in the presence of ferricyanide decreased only during room-temperature treatments. These results suggest that reaction centers of one pool of Photosystem II, non-QB-PS II, replace photoinhibited reaction centers at room temperature, while no replacement occurs at 1°C. A simulation of photoinhibition at 1°C supports this conclusion.
高光处理在室温下和 1°C 下进行，此时光系统 II 的扩散和酶依赖的修复过程处于最低水平。处理后，从处理过的叶片中分离的类囊体中测量电子转移活性和荧光诱导。当在 1°C 下进行光抑制处理时，设计为需要电子转移到质醌池的光系统 II 电子转移测定比从 H2O 到对苯醌的电子转移显示出更大的抑制，后者测量所有 PS II 中心。当在室温下进行光处理时，从 H2O 到对苯醌的电子转移比全链电子转移受到更大的抑制。在存在铁氰化物的情况下测量的可变荧光仅在室温处理期间下降。这些结果表明，在室温下，一个光系统 II 池的反应中心，非-QB-PS II，取代了光抑制的反应中心，而在 1°C 下则没有发生取代。1°C 下光抑制的模拟支持这一结论。
