Plants are the foundation of terrestrial ecosystems, and their colonization of land was probably facilitated by mutualistic associations with arbuscular mycorrhizal fungi. Following this founding event, plant diversification has led to the emergence of a tremendous diversity of mutualistic symbioses with microorganisms, ranging from extracellular associations to the most intimate intracellular associations, where fungal or bacterial symbionts are hosted inside plant cells. Here, through analysis of 271 transcriptomes and 116 plant genomes spanning the entire land-plant diversity, we demonstrate that a common symbiosis signalling pathway co-evolved with intracellular endosymbioses, from the ancestral arbuscular mycorrhiza to the more recent ericoid and orchid mycorrhizae in angiosperms and ericoid-like associations of bryophytes. By contrast, species forming exclusively extracellular symbioses, such as ectomycorrhizae, and those forming associations with cyanobacteria, have lost this signalling pathway. This work unifies intracellular symbioses, revealing conservation in their evolution across 450 million yr of plant diversification.

中文翻译：

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祖先的信号通路在细胞内形成共生的植物谱系中是保守的。

植物是陆地生态系统的基础，与丛枝菌根真菌的相互联系促进了它们在土地上的定殖。继这一发现事件之后，植物的多样化导致了与微生物的共生共生体的巨大多样性，从细胞外结合到最紧密的细胞内结合，其中真菌或细菌共生体都存在于植物细胞内。在这里，通过分析横跨整个陆地植物多样性的271个转录组和116个植物基因组，我们证明了一个常见的共生信号传导途径与细胞内共生酶共同进化，从先祖丛枝菌根到被子植物和被子植物中的类胡萝卜素和兰花菌根。苔藓植物类胡萝卜素的协会。相比之下，专门形成细胞外共生的物种，例如外生菌根，以及与蓝细菌形成关联的物种，已经失去了这一信号传导途径。这项工作统一了细胞内共生，揭示了它们在4.5亿年植物多样化中的进化过程中的保守性。