Huang Wei, Yang Ying-Jie, Zhang Shi-Bao
Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China.
Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Biochim Biophys Acta Bioenerg. 2019 May 1;1860(5):383-390. doi: 10.1016/j.bbabio.2019.03.007. Epub 2019 Mar 16.
The regulation of photosystem I (PSI) redox state under fluctuating light was investigated for four species using P700 measurement and electrochromic shift analysis. Species included the angiosperms Camellia japonica, Bletilla striata and Arabidopsis thaliana and the fern Cyrtomium fortunei. For the first seconds after transition from low to high light, all species showed relatively low levels of the proton gradient (ΔpH) across the thylakoid membranes. At this moment, PSI was highly oxidized in C. japonica and C. fortunei but was over-reduced in B. striata and A. thaliana. In B. striata and A. thaliana, the redox state of PSI was largely dependent on ΔpH. In contrast, the rapid oxidation of P700 in C. japonica was relatively independent of ΔpH, but was mainly dependent on the outflow of electrons to O via the water-water cycle. In the fern C. fortunei, PSI redox state was rapidly regulated by the fast photo-reduction of O rather than the ΔpH. These results indicate that mechanisms regulating PSI redox state under fluctuating light differ greatly between species. We propose that the water-water cycle is an important mechanism regulating the PSI redox state in angiosperms.
利用P700测量和电致变色位移分析，研究了四种植物在波动光下光系统I（PSI）氧化还原状态的调节情况。这些植物包括被子植物山茶、白芨和拟南芥以及蕨类植物贯众。在从低光转变为高光后的最初几秒内，所有植物类囊体膜上的质子梯度（ΔpH）水平相对较低。此时，山茶和贯众中的PSI高度氧化，而白芨和拟南芥中的PSI过度还原。在白芨和拟南芥中，PSI的氧化还原状态很大程度上取决于ΔpH。相比之下，山茶中P700的快速氧化相对独立于ΔpH，主要取决于通过水-水循环向O的电子流出。在蕨类植物贯众中，PSI氧化还原状态通过O的快速光还原而非ΔpH快速调节。这些结果表明，不同物种在波动光下调节PSI氧化还原状态的机制差异很大。我们认为水-水循环是调节被子植物中PSI氧化还原状态的重要机制。
