Ocean School, Yantai University, Yantai 264005, PR China.
Ocean School, Yantai University, Yantai 264005, PR China.
Plant Physiol Biochem. 2017 Apr;113:168-176. doi: 10.1016/j.plaphy.2017.02.011. Epub 2017 Feb 14.
Responses of electron transport to three levels of irradiation (20, 200, and 1200 μmol photons m s PAR; exposures called LL, ML and HL, respectively) were investigated in eelgrass (Zostera marina L.) utilizing the chlorophyll a fluorescence technique. Exposure to ML and HL reduced the maximum quantum yield of photosystem II (PSII) (Fv/Fm) and the maximum slope decrease of MR/MR (V), indicating the occurrence of photoinhibition of both PSII and photosystem I (PSI). A comparatively slow recovery rate of Fv/Fm due to longer half-life recovery time of PSII and 40% lower descending amplitude compared to other higher plants implied the poor resilience of the PSII. Comparatively, PSI demonstrated high resilience and cyclic electron transport (CEF) around PSI maintained high activity. With sustained exposure, the amplitudes of the kinetic components (L and L), the probability of electron transfer from PSII to plastoquinone pool (ψ), and the connectivity among PSII units decreased, accompanied by an enhancement of energy dissipation. Principle component analysis revealed that both V and Fv/Fm contributed to the same component, which was consistent with high connectivity between PSII and PSI, suggesting close coordination between both photosystems. Such coordination was likely beneficial for the adaption of high light. Exposure to LL significantly increased the activity of both PSI and CEF, which could lead to increased light harvesting. Moreover, smooth electron transport as indicated by the enhancement of L, L, ψ and the probability of electron transport to the final PSI acceptor sides, could contribute to an increase in light utilization efficiency.
利用叶绿素荧光技术研究了电子传递对三种辐射水平（20、200 和 1200 μmol 光子 m s PAR；分别称为 LL、ML 和 HL 暴露）的响应，研究对象为鳗草（Zostera marina L.）。ML 和 HL 的暴露降低了 PSII 的最大量子产量（Fv/Fm）和 MR/MR 的最大斜率降低（V），表明 PSII 和 PSI 的光抑制均发生。由于 PSII 的半衰期恢复时间较长且下降幅度比其他高等植物低 40%，因此 Fv/Fm 的恢复速率较慢，这表明 PSII 的恢复能力较差。相比之下，PSI 表现出较高的恢复能力和围绕 PSI 的循环电子传递（CEF）保持高活性。随着持续暴露，动力学组件（L 和 L）的幅度、电子从 PSII 向质体醌池转移的概率（ψ）以及 PSII 单元之间的连接性下降，同时伴随着能量耗散的增强。主成分分析表明，V 和 Fv/Fm 都对同一分量有贡献，这与 PSII 和 PSI 之间的高连接性一致，表明两个光系统之间的紧密协调。这种协调可能有利于适应高光。LL 暴露显著增加了 PSI 和 CEF 的活性，这可能导致光捕获增加。此外，如 L、L、ψ 和电子向最终 PSI 受体侧转移的概率的增强所表明的，平滑的电子传递可能有助于提高光利用效率。
