Photoprotection in a monophyletic branch of chlorophyte algae is independent of energy-dependent quenching (qE)
Photoprotection in a monophyletic branch of chlorophyte algae is independent of energy-dependent quenching (qE)
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DOI：
10.1111/nph.14435
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发表时间：
2017-05-01
期刊：
影响因子：
9.4
通讯作者：
Gould, Sven B.
中科院分区：
文献类型：
--
作者：
Christa, Gregor;Cruz, Sonia;Gould, Sven B.
光养生物需要确保高光合性能，同时抑制活性氧（ROS）诱导的应激发生在超光条件下。叶黄素循环（XC）与激发能非光化学猝灭（NPQ）的高能猝灭组分（qE）有关，被认为是光保护机制的必要组成部分。研究了绿藻科各主要支系中至少一种代表性植物的色素组成。我们寻找了色素的光依赖性转化，并研究了在不同光照条件下生长时，XC和qE组分对NPQ容量的贡献。在低光照条件下，单系植物苔藓科的一个类群中没有XC，但在强光条件下，10个苔藓科植物中有一个物种——杉叶蕨（Caulerpa cf. taxifolia）被触发了XC。尽管苔藓植物在高光条件下积累玉米黄质（Zea），但NPQ的形成与XC无关，与qE无关。苔藓门中与qE和xc无关的NPQ与普遍认为在叶绿体中普遍存在的NPQ相矛盾。在hl驯化的苔藓植物中，玉米积累很可能是功能性XC的残余。缺乏qE的单系藻类分类群的存在突出了对光保护机制进行广泛生物多样性研究的必要性。
Phototrophic organisms need to ensure high photosynthetic performance whilst suppressing reactive oxygen species (ROS)-induced stress occurring under excess light conditions. The xanthophyll cycle (XC), related to the high-energy quenching component (qE) of the nonphotochemical quenching (NPQ) of excitation energy, is considered to be an obligatory component of photoprotective mechanisms.The pigment composition of at least one representative of each major clade of Ulvophyceae (Chlorophyta) was investigated. We searched for a light-dependent conversion of pigments and investigated the NPQ capacity with regard to the contribution of XC and the qE component when grown under different light conditions.A XC was found to be absent in a monophyletic group of Ulvophyceae, the Bryopsidales, when cultivated under low light, but was triggered in one of the 10 investigated bryopsidalean species, Caulerpa cf. taxifolia, when cultivated under high light. Although Bryopsidales accumulate zeaxanthin (Zea) under high-light (HL) conditions, NPQ formation is independent of a XC and not related to qE.qE- and XC-independent NPQ in the Bryopsidales contradicts the common perception regarding its ubiquitous occurrence in Chloroplastida. Zea accumulation in HL-acclimated Bryopsidales most probably represents a remnant of a functional XC. The existence of a monophyletic algal taxon that lacks qE highlights the need for broad biodiversity studies on photoprotective mechanisms.