Different patterns of carotenoid composition and photosynthesis acclimation in two tropical red algae
Different patterns of carotenoid composition and photosynthesis acclimation in two tropical red algae
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DOI：
10.1007/s00227-005-0174-3
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发表时间：
2006-01
期刊：
影响因子：
2.4
通讯作者：
Markus Andersson;Hendrik Schubert;Marianne Pedersén;P. Snoeijs
中科院分区：
文献类型：
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作者：
Markus Andersson;Hendrik Schubert;Marianne Pedersén;P. Snoeijs
为了能够生存，浅海沃茨中的大型海藻需要短期适应环境快速变化的机制。最重要的是通过保护PS II免受光氧化损伤来调节光合作用效率的机制。类胡萝卜素、叶黄素循环和非光化学猝灭（NPQ）是这种保护机制的核心成分。红藻作为一个群体不具有普遍的类胡萝卜素成分。我们筛选了10种红藻，并选择了两个物种，起源于类似的生态条件，但具有不同的类胡萝卜素组成，用于辐照驯化实验。我们选择了热带潮间带物种Gracilaria domingensis和Kappaphycus alvarezii，分别以花药黄质和叶黄素为主要叶黄素。同时在体内荧光和O2进化实验进行了不同的辐照水平，这使得直接比较的整体光合性能与NPQ。叶黄素（紫黄质、玉米黄质、β-隐黄质和一种未知的类胡萝卜素）在G. domingensis，但不响应突然暴露于光。因此，NPQ与短期光适应过程中的任何叶黄素循环都不相关。domingens的光合速率比K高5倍。alvarezii，这可能是由于K. alvarezii。叶绿素比总光合速率在施钾条件下较高。alvarezii，但两个物种的净率相同。domingsis显示，在暴露于辐照后，NPQ立即强烈发作，随后下调至所需的NPQ水平。墨水alvarezii NPQ缓慢增加，直到达到所需的NPQ水平。在高辐照度下G. domingensis下调光合作用，而K. Alvarezi在2，000 μmol光子数m−2s− 1时仍继续产生O2，而NPQ没有增加。K. alvarezii可能提供短期收益，但有氧化损伤的风险。NPQ在G.在亚饱和光照下的domingensiseven以及当NPQ饱和时光合作用的下调可能为该物种在田间变化的光照条件下提供竞争优势。
To be able to survive, marine macroalgae in shallow coastal waters need mechanisms for short-term acclimation to fast changes in their environment. Of major importance are mechanisms that regulate the efficiency of photosynthesis by protecting PS II from photo-oxidative damage. Carotenoids, xanthophyll cycles and non-photochemical quenching (NPQ) are central constituents of such protection mechanisms. Red algae as a group do not have a universal carotenoid composition. We screened ten red algal species and selected two species, originating from similar ecological conditions but with different carotenoid compositions, for use in irradiance-acclimation experiments. We selected the tropical intertidal speciesGracilaria domingensisandKappaphycus alvareziiwith antheraxanthin and lutein as major xanthophylls, respectively. Simultaneous in vivo fluorescence and O2evolution experiments were performed at different irradiance levels, which allowed a direct comparison of overall photosynthetic performance with NPQ. Interconversions of xanthophylls (violaxanthin, zeaxanthin, β-cryptoxanthin and one unidentified carotenoid) did occur inG. domingensis, but not in response to sudden exposure to light. Thus, NPQ was not correlated with any xanthophyll cycle during short-term acclimation to light.G. domingensishad five times higher weight-specific photosynthetic rates thanK. alvarezii, which can be explained by the thicker thallus ofK. alvarezii. Chlorophyll-specific gross photosynthetic rates were higher inK. alvarezii, but net rates were the same for both species.G. domingensisshowed an immediate strong onset of NPQ upon exposure to irradiance, followed by downregulation to the NPQ level required. InK. alvareziiNPQ increased slowly until the required NPQ level was reached. At high irradianceG. domingensisdownregulated photosynthesis whileK. alvareziicontinued to produce O2even at 2,000 μmol photons m−2s−1without NPQ increase. The strategy ofK. alvareziimay provide short-term gains but with the risk of oxidative damage. The fast onset of NPQ inG. domingensiseven at subsaturating irradiance as well as downregulation of photosynthesis when NPQ is saturated might provide this species with a competitive advantage under conditions of changing irradiance in the field.