Physiological Role of Cyclic Electron Flow in Higher Plants

As an important alternative electron flow,cyclic electron flow (CEF) is essential for photosynthesis in many higher plants.The CEF-dependent generation of proton gradient across thylakoid membranes not only activates ATP synthesis but also protects photosystemⅡfrom photoinhibition through activating non-photochemical quenching and stabilizing oxygen-evolving complexes. Furthermore,CEF can alleviate the over-reduction of acceptor side of photosystemⅠ(PSⅠ) and generation of superoxide anion,and thus protect PSⅠ from photoinhibition.This review briefly summarizes the pathways of CEF,roles of CEF,response of CEF to environmental stress,and proposes perspectives.