Xanthophyll cycle - a mechanism protecting plants against oxidative stress
Xanthophyll cycle - a mechanism protecting plants against oxidative stress
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DOI：
10.1179/174329211x13020951739938
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发表时间：
2011-03-01
期刊：
影响因子：
3.8
通讯作者：
Strzalka, Kazimierz
中科院分区：
文献类型：
--
作者：
Latowski, Dariusz;Kuczynska, Paulina;Strzalka, Kazimierz
在光合作用的生物体中已经描述了六个不同的叶黄素循环。它们都保护光合作用装置不受光诱导的氧化胁迫造成的光损伤。在叶绿体中，过激发条件导致NADP池的过度还原和超氧化物的产生，这些超氧化物随后可以被代谢成过氧化氢或羟基自由基，以及其他活性氧物种(ROS)。另一方面，光系统的过度激发导致了叶绿素激发态寿命的延长，增加了叶绿素三重态与三重态氧反应形成单氧的几率，即另一种ROS。叶黄素循环的光依赖阶段的产物在保护植物免受氧化胁迫方面起着重要作用，这些氧化胁迫不仅是由过量的光产生的，也是由其他产生ROS的因素产生的，如干旱、冷害、高温、衰老或盐分胁迫。第四，主要是假设性的，解释叶黄素循环在氧化应激中的保护作用的机制。其中一种是叶黄素环光相副产物对过激发的直接猝灭，另三种是叶黄素环类胡萝卜素间接参与光保护过程。它们包括：(1)依赖于聚集的捕光络合物(LHCII)猝灭对过激发的间接猝灭；(2)LHCII中的光驱动机制；(3)基于Chla和Zx之间电荷转移猝灭的模型。此外，还给出了叶黄素循环色素在模型体系中抗氧化性能的研究结果。
Six different xanthophyll cycles have been described in photosynthetic organisms. All of them protect the photosynthetic apparatus from photodamage caused by light-induced oxidative stress. Overexcitation conditions lead, in the chloroplast, to the over-reduction of the NADP pool and production of superoxide, which can subsequently be metabolized to hydrogen peroxide or a hydroxyl radical, other reactive oxygen species (ROS). On the other hand, overexcitation of photosystems leads to an increased lifetime of the chlorophyll excited state, increasing the probability of chlorophyll triplet formation which reacts with triplet oxygen forming single oxygen, another ROS. The products of the light-dependent phase of xanthophyll cycles play an important role in the protection against oxidative stress generated not only by an excess of light but also by other ROS-generating factors such as drought, chilling, heat, senescence, or salinity stress. Four, mainly hypothetical, mechanisms explaining the protective role of xanthophyll cycles in oxidative stress are presented. One of them is the direct quenching of overexcitation by products of the light phase of xanthophyll cycles and three others are based on the indirect participation of xanthophyll cycle carotenoids in the process of photoprotection. They include: (1) indirect quenching of overexcitation by aggregation-dependent light-harvesting complexes (LHCII) quenching; (2) light-driven mechanisms in LHCII; and (3) a model based on charge transfer quenching between Chl a and Zx. Moreover, results of the studies on the antioxidant properties of xanthophyll cycle pigments in model systems are also presented.