The light reactions in photosynthesis convert light energy into chemical energy in the form of ATP and drive the production of NADPH from NADP+. The reactions involve two types of electron flow in the chloroplast. While linear electron transport generates both ATP and NADPH, photosystem I cyclic electron transport is exclusively involved in ATP synthesis. The physiological significance of photosystem I cyclic electron transport has been underestimated, and our knowledge of the machineries involved remains very limited. However, recent genetic approaches using Arabidopsis thaliana have clarified the essential functions of this electron flow in both photoprotection and photosynthesis. Based on several lines of evidence presented here, it is necessary to reconsider the fundamental mechanisms of chloroplast energetics.

中文翻译：

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光系统 I 周围的循环电子传输：遗传方法

光合作用中的光反应将光能转化为 ATP 形式的化学能，并驱动 NADP+ 产生 NADPH。反应涉及叶绿体中两种类型的电子流。虽然线性电子传递产生 ATP 和 NADPH，但光系统 I 循环电子传递仅参与 ATP 合成。光系统 I 循环电子传输的生理意义被低估了，我们对所涉及的机制的了解仍然非常有限。然而，最近使用拟南芥的遗传方法阐明了这种电子流在光保护和光合作用中的基本功能。基于这里提供的几条证据，有必要重新考虑叶绿体能量学的基本机制。