Slow zeaxanthin accumulation and the enhancement of CP26 collectively contribute to an atypical non-photochemical quenching in macroalga Ulva prolifera under high light
Slow zeaxanthin accumulation and the enhancement of CP26 collectively contribute to an atypical non-photochemical quenching in macroalga Ulva prolifera under high light
复制标题
玉米黄质的缓慢积累和 CP26 的增强共同导致强光下大型藻石莼的非典型非光化学猝灭
DOI：
10.1111/jpy.12958
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发表时间：
2020-01-13
影响因子：
2.9
通讯作者：
Wang, Guangce
中科院分区：
文献类型：
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作者：
Gao, Shan;Zheng, Zhenbing;Wang, Guangce
非光化学猝灭（Non-photochemical quenching， NPQ）是植物在强光胁迫下的一种重要的光保护机制，可以耗散多余的能量，进一步保护光合机构。NPQ可以被分解为几个组成部分：qE、qZ和qI。总的来说，NPQ是由两种独立的机制催化的，由单体光收集复合物（LHCII）蛋白催化的快活化猝灭和由LHCII三聚体催化的慢活化猝灭，这两个过程都依赖于玉米黄质，但程度不同。本研究对潮间带绿藻藻藻（Ulva prolifera）的NPQ进行了研究，发现其NPQ缺乏快速激活猝灭，对二硫苏糖醇（DTT）的敏感性远高于对二环己基碳二亚胺（DCCD）的敏感性。进一步的结果表明，与拟南芥和苔藓小立藓不同，增菌LHC单体蛋白仅含有CP29和CP26，缺乏CP24。此外，CP26的表达水平在强光照射后显著增加，但两种重要的光保护蛋白（PsbS和光收集复合应力相关蛋白[LhcSR]）的浓度在相同条件下没有变化。对玉米黄素循环色素的分析表明，在强光照射下，玉米黄素的合成是渐进的，远慢于玉米黄素的合成，DTT能有效抑制玉米黄素的合成。基于这些结果，我们推测CP26的增强和玉米黄质积累的缓慢提供了一个非典型的NPQ，使这种绿色大藻很好地适应了潮间带环境。
Non-photochemical quenching (NPQ) is an important photoprotective mechanism in plants, which dissipates excess energy and further protects the photosynthetic apparatus under high light stress. NPQ can be dissected into a number of components: qE, qZ, and qI. In general, NPQ is catalyzed by two independent mechanisms, with the faster-activated quenching catalyzed by the monomeric light-harvesting complex (LHCII) proteins and the slowly activated quenching catalyzed by LHCII trimers, both processes depending on zeaxanthin but to different extent. Here, we studied the NPQ of the intertidal green macroalga, Ulva prolifera, and found that the NPQ of U. prolifera lack the faster-activated quenching, and showed much greater sensitivity to dithiothreitol (DTT) than to dicyclohexylcarbodiimide (DCCD). Further results suggested that the monomeric LHC proteins in U. prolifera included only CP29 and CP26, but lacked CP24, unlike Arabidopsis thaliana and the moss Physcomitrella patens. Moreover, the expression levels of CP26 increased significantly following exposure to high light, but the concentrations of the two important photoprotective proteins (PsbS and light-harvesting complex stress-related [LhcSR]) did not change upon the same conditions. Analysis of the xanthophyll cycle pigments showed that, upon exposure to high light, zeaxanthin synthesis in U. prolifera was gradual and much slower than that in P. patens, and could effectively be inhibited by DTT. Based on these results, we speculate the enhancement of CP26 and slow zeaxanthin accumulation provide an atypical NPQ, making this green macroalga well adapted to the intertidal environments.