Mitochondrial alternative oxidase pathway protects plants against photoinhibition by alleviating inhibition of the repair of photodamaged PSII through preventing formation of reactive oxygen species in Rumex K-1 leaves.
Mitochondrial alternative oxidase pathway protects plants against photoinhibition by alleviating inhibition of the repair of photodamaged PSII through preventing formation of reactive oxygen species in Rumex K-1 leaves.
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DOI：
10.1111/j.1399-3054.2011.01514.x
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发表时间：
2011-12
影响因子：
6.4
通讯作者：
Li-tao Zhang;Zishan Zhang;Hui-Yuan Gao;Z. Xue;Cheng Yang;Xiang-Long Meng;Q. Meng
中科院分区：
文献类型：
--
作者：
Li-tao Zhang;Zishan Zhang;Hui-Yuan Gao;Z. Xue;Cheng Yang;Xiang-Long Meng;Q. Meng
研究了鲁梅克斯K-1叶片线粒体交替氧化酶（AOX）途径在光抑制中的作用。AOX途径的抑制降低了NADP-苹果酸脱氢酶（EC 1.1.1.82，NADP-MDH）的初始活性和光合末端电子受体的池大小，导致光系统I（PSI）受体侧的过度还原。PSI受体侧的过度还原进一步抑制了电子从光系统II（PSII）反应中心向PSII受体侧的传递，表现为J阶处的相对可变荧光（V（J））的增加，导致强光下每个活性反应中心（RC）的光合光吸收和能量利用之间的不平衡，从而导致PSII反应中心的过度激发。PSI受体侧的过度还原和PSII反应中心的过度兴奋促进了活性氧（ROS）的积累，从而抑制了光损伤PSII的修复。然而，AOX途径的抑制并没有改变叶绿体D1蛋白合成抑制剂氯霉素存在下的强光下的光抑制水平，表明AOX途径的抑制并没有直接加速光损伤PSII。所有这些结果表明AOX途径通过阻止ROS的过度产生，最大限度地减少对光损伤PSII修复的抑制，从而在保护植物免受光抑制中发挥重要作用。
The purpose of this study was to explore how the mitochondrial AOX (alternative oxidase) pathway alleviates photoinhibition in Rumex K-1 leaves. Inhibition of the AOX pathway decreased the initial activity of NADP-malate dehydrogenase (EC 1.1.1.82, NADP-MDH) and the pool size of photosynthetic end electron acceptors, resulting in an over-reduction of the photosystem I (PSI) acceptor side. The over-reduction of the PSI acceptor side further inhibited electron transport from the photosystem II (PSII) reaction centers to the PSII acceptor side as indicated by an increase in V(J) (the relative variable fluorescence at J-step), causing an imbalance between photosynthetic light absorption and energy utilization per active reaction center (RC) under high light, which led to the over-excitation of the PSII reaction centers. The over-reduction of the PSI acceptor side and the over-excitation of the PSII reaction centers enhanced the accumulation of reactive oxygen species (ROS), which inhibited the repair of the photodamaged PSII. However, the inhibition of the AOX pathway did not change the level of photoinhibition under high light in the presence of the chloroplast D1 protein synthesis inhibitor chloramphenicol, indicating that the inhibition of the AOX pathway did not accelerate the photodamage to PSII directly. All these results suggest that the AOX pathway plays an important role in the protection of plants against photoinhibition by minimizing the inhibition of the repair of the photodamaged PSII through preventing the over-production of ROS.