Targeted metagenomics and ecology of globally important uncultured eukaryotic phytoplankton
Targeted metagenomics and ecology of globally important uncultured eukaryotic phytoplankton
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DOI：
10.1073/pnas.1001665107
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发表时间：
2010-08-17
影响因子：
11.1
通讯作者：
Worden, Alexandra Z.
中科院分区：
文献类型：
--
作者：
Cuvelier, Marie L.;Allen, Andrew E.;Worden, Alexandra Z.
在真核生物中，四种主要的浮游植物谱系负责海洋光合作用; prymnesiophytes，alveolates，stratomiles和prasinophytes。然而，个体分类群的贡献并不为人所知，仅对后两个谱系的基因组进行了分析。微小的“picoacetonic”成员prymnesiophyte谱系长期以来一直被推断为生态重要，但仍然缺乏特点。在这里，我们研究pico prymnesiophyte的进化历史和生态使用培养独立的方法。18 S rRNA基因分析表明，微微型原生植物属于广泛分布的未栽培类群。因此，我们使用靶向宏基因组学分析未培养的pico-prymnesiophytes分选从亚热带北大西洋沃茨通过流式细胞术。这些数据揭示了一个复合的核编码基因库，具有强烈的绿色血统的联系，这与质体基因组所示的进化历史形成鲜明对比。测得的微微prymnesiophyte的增长速度很快，在这一地区，导致初级生产的贡献类似的蓝藻原绿球藻。平均而言，pico-prymnesiophytes形成了25%的全球picophytoplankton生物量，在五个地理省的不同贡献，从热带到亚极地系统。可能有助于成功的因素包括高基因密度和可能参与防御和营养吸收的基因。我们的研究结果具有深远的影响，超越pico prymnesiophytes，prasinophytes和straverniles。例如，普遍存在的推定含镍的超氧化物歧化酶（SOD），而不是含铁的SOD，似乎是一种常见的适应真核浮游植物减少铁配额在低铁的现代海洋。此外，高度镶嵌基因库，虽然组成不同的每一个主要的真核生物谱系，现在似乎是成功的海洋浮游植物的一个基本方面。
Among eukaryotes, four major phytoplankton lineages are responsible for marine photosynthesis; prymnesiophytes, alveolates, stramenopiles, and prasinophytes. Contributions by individual taxa, however, are not well known, and genomes have been analyzed from only the latter two lineages. Tiny "picoplanktonic" members of the prymnesiophyte lineage have long been inferred to be ecologically important but remain poorly characterized. Here, we examine pico-prymnesiophyte evolutionary history and ecology using cultivation-independent methods. 18S rRNA gene analysis showed pico-prymnesiophytes belonged to broadly distributed uncultivated taxa. Therefore, we used targeted metagenomics to analyze uncultured pico-prymnesiophytes sorted by flow cytometry from subtropical North Atlantic waters. The data reveal a composite nuclear-encoded gene repertoire with strong green-lineage affiliations, which contrasts with the evolutionary history indicated by the plastid genome. Measured pico-prymnesiophyte growth rates were rapid in this region, resulting in primary production contributions similar to the cyanobacterium Prochlorococcus. On average, pico-prymnesiophytes formed 25% of global picophytoplankton biomass, with differing contributions in five biogeographical provinces spanning tropical to subpolar systems. Elements likely contributing to success include high gene density and genes potentially involved in defense and nutrient uptake. Our findings have implications reaching beyond pico-prymnesiophytes, to the prasinophytes and stramenopiles. For example, prevalence of putative Ni-containing superoxide dismutases (SODs), instead of Fe-containing SODs, seems to be a common adaptation among eukaryotic phytoplankton for reducing Fe quotas in low-Fe modern oceans. Moreover, highly mosaic gene repertoires, although compositionally distinct for each major eukaryotic lineage, now seem to be an underlying facet of successful marine phytoplankton.