CONCERNING A DUAL FUNCTION OF COUPLED CYCLIC ELECTRON-TRANSPORT IN LEAVES
CONCERNING A DUAL FUNCTION OF COUPLED CYCLIC ELECTRON-TRANSPORT IN LEAVES
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DOI：
10.1104/pp.100.4.1621
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发表时间：
1992-12-01
期刊：
影响因子：
7.4
通讯作者：
WALKER, D
中科院分区：
文献类型：
--
作者：
HEBER, U;WALKER, D
耦合循环电子传递除了在ATP合成中起作用外，还在保护叶片免受光抑制中起作用。在叶片中，就像在重组的类囊体系统中一样，循环电子传递需要“平衡”，即光系统I （PSI）还原侧的电子可用性以及光系统II （PSII）和PSI之间一些氧化的质体醌的存在。当二氧化碳在高光强下限制光合作用时，特别是当气孔由于水分胁迫而部分或完全关闭时，在自我调节的胁迫条件下，耦合循环电子传递通过帮助建立足够大的质子梯度来控制线性电子传递，从而降低PSII活性和流向PSI的电子流。这使得PSII的电子捐赠和可用电子受体的电子消耗达到平衡，在这种平衡中，PSI比在快速碳同化过程中更容易被氧化。避免电子传递链的过度还原是有效保护光合装置免受光失活的先决条件。
Coupled cyclic electron transport is assigned a role in the protection of leaves against photoinhibition in addition to its role in ATP synthesis. In leaves, as in reconstituted thylakoid systems, cyclic electron transport requires "poising," i.e. availability of electrons at the reducing side of photosystem I (PSI) and the presence of some oxidized plastoquinone between photosystem II (PSII) and PSI. Under self-regulatory poising conditions that are established when carbon dioxide limits photosynthesis at high light intensities, and particularly when stomata are partially or fully closed as a result of water stress, coupled cyclic electron transport controls linear electron transport by helping to establish a proton gradient large enough to decrease PSII activity and electron flow to PSI. This brings electron donation by PSII, and electron consumption by available electron acceptors, into a balance in which PSI becomes more oxidized than it is during fast carbon assimilation. Avoidance of overreduction of the electron transport chain is a prerequisite for the efficient protection of the photosynthetic apparatus against photoinactivation.