Microscopic algae release organic compounds to the region immediately surrounding their cells, known as the phycosphere, constituting a niche for colonization by heterotrophic bacteria. These bacteria take up algal photoassimilates and provide beneficial functions to their host, in a process that resembles the establishment of microbial communities associated with the roots and rhizospheres of land plants. Here, we characterize the microbiota of the model alga Chlamydomonas reinhardtii and reveal extensive taxonomic and functional overlap with the root microbiota of land plants. Reconstitution experiments using synthetic communities derived from C. reinhardtii and Arabidopsis thaliana show that phycosphere and root bacteria assemble into taxonomically equivalent communities on either host. We show that provision of diffusible metabolites is not sufficient for phycosphere community establishment, which additionally requires physical proximity to the host. Our data suggests that the microbiota of photosynthetic organisms, including green algae and flowering plants, assembles according to core ecological principles.

中文翻译：

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莱茵衣藻衣藻层的表征揭示了植物微生物群的保守特征

微观藻类将有机化合物释放到紧邻其细胞的区域，称为藻圈，从而构成了异养细菌定居的利基。这些细菌吸收藻类的光同化物并为其宿主提供有益的功能，其过程类似于建立与陆地植物根部和根际相关的微生物群落。在这里，我们表征了藻类莱茵衣藻的微生物群，并揭示了与陆地植物根部微生物群的广泛分类和功能重叠。使用源自莱茵衣藻和拟南芥的合成群落进行的重建实验表明，在任一宿主上，藻圈和根细菌都组装成分类学上等效的群落。我们显示，提供扩散性代谢物不足以建立藻圈群落，这还需要与宿主物理接近。我们的数据表明，光合生物的微生物群（包括绿藻和开花植物）是根据核心生态原理组装的。