Contrasting photoacclimation costs in ecotypes of the marine eukaryotic picoplankter Ostreococcus
Contrasting photoacclimation costs in ecotypes of the marine eukaryotic picoplankter Ostreococcus
复制标题
海洋真核超微型浮游生物骨球菌生态型的光驯化成本对比
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
Douglas A. Campbell
中科院分区：
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作者：
Christophe Six;Zoe V. Finkel;Francisco Rodriguez;Dominique Marie;F. Partensky;Douglas A. Campbell
链球菌是已知的最小的海洋微核生物，包括低光和高光生态型。确定链球菌属之间生态位划分的依据。从热带大西洋真光层底部分离到的菌株RCC809和泻湖菌株陶瑞乳杆菌，在普通营养补充条件下，研究了−2 S−1至−2 S−1在15µm o l光子照射下的光生理特性。随着生长光强的增加，两个菌株都下调了细胞中叶绿素a和b(Chla和Chlb)的含量，增加了与非光化学激发猝灭相关的叶黄素去环氧化作用，并积累了叶黄素。核酮糖-1，5-二磷酸羧化酶/加氧酶含量保持相对稳定。在15-80微克分子光子m−2 S−1，O.sp.RCC809的生长速率相当或略高，Chla较低，Chlb/Chla比值较高，光系统II(PSII)天线较大。金丝桃对生长光照的响应更具表型可塑性，其生长速率、Chla、光系统细胞含量和PSII细胞吸收截面的动态范围较大。对光驯化所需的氨基酸和氮素成本的估算表明，深海大洋Osp.RCC809在很大程度上依赖于PSII天线尺寸的较低氮气成本变化来实现有限范围的σ类型的光适应。O.sp.然而，RCC809在强光下受到光抑制。这种有限的光适应能力与热带大西洋真光层底部稳定的弱光和营养条件相适应。在多变的、高营养的泻湖环境中，金鱼草可以使用成本更高的n型光系统内容驯化来利用更广泛的光。
Ostreococcus, the smallest known marine picoeukaryote, includes low‐ and high‐light ecotypes. To determine the basis for niche partitioning between Ostreococcus sp. RCC809, isolated from the bottom of the tropical Atlantic euphotic zone, and the lagoon strain Ostreococcus tauri, we studied their photophysiologies under growth irradiances from 15 µmol photons m−2 s−1 to 800 µmol photons m−2 s−1 with a common nutrient replete regime. With increasing growth irradiance, both strains down‐regulated cellular chlorophyll a and chlorophyll b (Chl a and Chl b) content, increased xanthophyll de‐epoxidation correlated with nonphotochemical excitation quenching, and accumulated lutein. Ribulose‐1,5‐bisphosphate carboxylase/oxygenase content remained fairly stable. Under low‐growth irradiances of 15‐80 µmol photons m−2 s−1, O. sp. RCC809 had equivalent or slightly higher growth rates, lower Chl a, a higher Chl b : Chl a ratio, and a larger photosystem II (PSII) antenna than O. tauri. O. tauri was more phenotypically plastic in response to growth irradiance, with a larger dynamic range in growth rate, Chl a, photosystem cell content, and cellular absorption cross‐section of PSII. Estimating the amino acid and nitrogen costs for photoacclimation showed that the deep‐sea oceanic O. sp. RCC809 relies largely on lower nitrogen cost changes in PSII antenna size to achieve a limited range of σ‐type light acclimation. O. sp. RCC809, however, suffers photoinhibition under higher light. This limited capacity for photoacclimation is compatible with the stable low‐light and nutrient conditions at the base of the euphotic layer of the tropical Atlantic Ocean. In the more variable, high‐nutrient, lagoon environment, O. tauri can afford to use a higher cost n‐type acclimation of photosystem contents to exploit a wider range of light.