A Dual Strategy to Cope with High Light in Chlamydomonas reinhardtii
A Dual Strategy to Cope with High Light in Chlamydomonas reinhardtii
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DOI：
10.1105/tpc.112.108274
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发表时间：
2013-02-01
期刊：
影响因子：
11.6
通讯作者：
Finazzi, Giovanni
中科院分区：
文献类型：
--
作者：
Allorent, Guillaume;Tokutsu, Ryutaro;Finazzi, Giovanni
光的吸收超过光合电子传递的能力对光合生物是有害的。存在几种避免光损伤的机制，这些机制统称为非光化学猝灭。这个术语至少包括两个主要过程。状态转换（qT）表示光系统II和i的相对天线尺寸的变化。高能猝灭（qE）是由管腔酸化引发的光能热耗散增加。为了研究qE和qT在光保护中的作用，我们在莱茵衣藻（Chlamydomonas reinhardtii）中通过将状态转换缺陷突变体（stt7-9）与qE能力大幅降低的菌株（npq4）杂交，产生了一个突变体（npq4 stt7-9）。对野生型、单突变体和双突变体的比较表型分析表明，状态转换和qE都是由强光诱导的。此外，与单突变体和野生型相比，双突变体表现出更高的光敏性。因此，我们认为除了qE，在细胞的强光驯化过程中，状态转变也起着光保护作用，很可能是通过减少过氧化氢的产生。从光系统II中多余光的热耗散和/或天线的物理位移相关的相对光保护效益的角度讨论了这些结果。
Absorption of light in excess of the capacity for photosynthetic electron transport is damaging to photosynthetic organisms. Several mechanisms exist to avoid photodamage, which are collectively referred to as nonphotochemical quenching. This term comprises at least two major processes. State transitions (qT) represent changes in the relative antenna sizes of photosystems II and I. High energy quenching (qE) is the increased thermal dissipation of light energy triggered by lumen acidification. To investigate the respective roles of qE and qT in photoprotection, a mutant (npq4 stt7-9) was generated in Chlamydomonas reinhardtii by crossing the state transition-deficient mutant (stt7-9) with a strain having a largely reduced qE capacity (npq4). The comparative phenotypic analysis of the wild type, single mutants, and double mutants reveals that both state transitions and qE are induced by high light. Moreover, the double mutant exhibits an increased photosensitivity with respect to the single mutants and the wild type. Therefore, we suggest that besides qE, state transitions also play a photoprotective role during high light acclimation of the cells, most likely by decreasing hydrogen peroxide production. These results are discussed in terms of the relative photoprotective benefit related to thermal dissipation of excess light and/or to the physical displacement of antennas from photosystem II.