Proton gradient regulation 5‐like photosynthetic phenotype 1 (PGRL1)‐dependent cyclic electron transport around photosystem I (PSI) plays important roles in the response to different stresses, including high light. Although the function of PGRL1 in higher plants and green algae has been thoroughly investigated, little information is available on the molecular mechanism of PGRL1 in diatoms. We created PGRL1 overexpression and knockdown transformants of Phaeodactylum tricornutum, the diatom model species, and investigated the impact on growth and photosynthesis under constant and fluctuating light conditions. PGRL1 over‐accumulation resulted in significant decreases in growth rate and apparent photosystem II (PSII) activity and led to an opposing change of apparent PSII activity when turning to high light, demonstrating a similar influence on photosynthesis as a PSII inhibitor. Our results suggested that PGRL1 overexpression can reduce the apparent efficiency of PSII and inhibit growth in P. tricornutum. These findings provide physiological evidence that the accumulation of PGRL1 mainly functions around PSII instead of PSI.

中文翻译：

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PGRL1在三角藻中的过度表达抑制了生长并降低了表观PSII活性。

质子梯度调节5样光合作用表型1（PGRL1）依赖光电子系统I（PSI）周围的循环电子传输在响应不同的压力（包括强光）中起重要作用。尽管已经深入研究了PGRL1在高等植物和绿藻中的功能，但关于硅藻中PGRL1分子机制的信息很少。我们创建了三角角芽孢杆菌PGRL1过表达和敲低转化体，硅藻模型物种，并研究了在不断变化的光照条件下对生长和光合作用的影响。PGRL1过度积累会导致生长速率和明显的光系统II（PSII）活性显着下降，并在转向高光时导致表观PSII活性发生相反的变化，这与PSII抑制剂对光合作用的影响相似。我们的结果表明，PGRL1的过表达可以降低PSII的表观效率，并抑制三角假单胞菌的生长。这些发现提供了生理证据，表明PGRL1的积累主要在PSII而非PSI周围起作用。