PSI-Driven Cyclic Electron Flow Allows Intertidal Macro-Algae Ulva sp (Chlorophyta) to Survive in Desiccated Conditions
PSI-Driven Cyclic Electron Flow Allows Intertidal Macro-Algae Ulva sp (Chlorophyta) to Survive in Desiccated Conditions
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PSI 驱动的循环电子流使潮间带大型藻类石莼 (绿藻) 在干燥条件下生存
DOI：
10.1093/pcp/pcr038
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发表时间：
2011-05-01
影响因子：
4.9
通讯作者：
Pan, Guanghua
中科院分区：
文献类型：
--
作者：
Gao, Shan;Shen, Songdong;Pan, Guanghua
2008年青岛沿着发生的绿色潮，对2008年北京奥运会帆船比赛产生了不利影响。鉴于其重要意义，我们研究了石莼在脱水和复水过程中光合系统的光合性能和光合电子传递的变化。在脱水过程中，石莼PSII活性逐渐下降，表现为最大量子产额和有效量子产额的下降，而PSI活性则波动较大。相反，PSII的电子传递速率接近零，在严重的干燥水平，但PSI的电子传递，仍然运作，可以有效地抑制由一个特定的抑制剂。此外，PSI的电子传递在脱水菌体复水过程中恢复快于PSII。所有这些结果表明，在干燥的石莼中线性电子流被取消，而环PSI活性显著升高，在严重的脱水水平下仍有活性，并且比PSII活性恢复得更快。基于这些结果，我们得出结论，PSI驱动的循环电子流可能提供了脱水耐受性和额外的灵活性，在干燥条件下的细胞生理，这可能是最重要的因素之一，使石莼。适合经历每天周期的干燥在低潮和在高潮的复水。
Ulva sp. (Chlorophyta) is a representative species of the intertidal macro-algae responsible for the green tides that occurred along the shores of Qingdao in 2008 and had detrimental effects on the preparation for the 2008 Beijing Olympic Games sailing competition. In view of its significance, we have investigated the photosynthetic performance of the photosystems and the changes in photosynthetic electron transport that occur during desiccation and rehydration of Ulva sp. The PSII activity in Ulva sp. declined gradually during the course of desiccation, which was reflected by the decreased maximum quantum yield and effective quantum yield, whereas the PSI activity fluctuated significantly. In contrast, the electron transport rates of PSII approached zero at severe levels of desiccation, but the electron transport of PSI, which still operated, could be suppressed effectively by a specific inhibitor. Furthermore, the electron transport of PSI during rehydration of desiccated thalli was recovered faster than that of PSII. All these results implied that the linear electron flow was abolished in desiccated Ulva sp., whereas the cyclic PSI activity was significantly elevated, was still active at severe levels of desiccation and could be restored faster than PSII activity. Based on these results, we concluded the PSI-driven cyclic electron flow might provide desiccation tolerance and additional flexibility for the cell physiology of Ulva sp. under desiccation conditions, which might be one of the most important factors that make Ulva sp. well suited to experience daily cycles of desiccation at low tide and rehydration at high tide.