Healthy plants are colonized by microorganisms from the surrounding environment, which form stable communities and provide beneficial services to the host. Culture-independent profiling of the bacterial root microbiota shows that different plant species are colonized by distinct bacterial communities, even if they share the same habitat. It is, however, not known to what extent the host actively selects these communities and whether commensal bacteria are adapted to a specific plant species. Here, we report a sequence-indexed culture collection from roots and nodules of the model legume Lotus japonicus that contains representatives from the majority of species found in culture-independent profiles. Using taxonomically paired synthetic communities from L. japonicus and the crucifer Arabidopsis thaliana in a multi-species gnotobiotic system, we detect clear signatures of host preference among commensal bacteria in a community context, but not in mono-associations. Sequential inoculation of either host reveals strong priority effects during the assembly of the root microbiota, where established communities are resilient to invasion by late-comers. However, we found that host preference by commensal bacteria confers a competitive advantage in their native host. We reveal that host preference is prevalent in commensal bacteria from diverse taxonomic groups and that this trait is directly linked to their invasiveness into standing root-associated communities.

中文翻译：

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寄主的喜好和对莲和拟南芥根微生物群落的入侵

健康植物被周围环境中的微生物所定植，这些微生物形成稳定的群落并为寄主提供有益的服务。细菌根微生物群的不依赖培养的分析表明，即使不同植物物种共享相同的生境，它们也会被不同的细菌群落所定殖。然而，还不清楚宿主在多大程度上主动选择这些群落以及共生细菌是否适合特定的植物物种。在这里，我们报告从豆科植物日本莲模型的根和结节开始的序列索引培养物收集，其中包含来自与文化无关的档案中发现的大多数物种的代表。使用分类学上日本血吸虫和十字花科的合成群落拟南芥在多种物种的gnotobiotic系统中，我们检测到社区环境中共生细菌中宿主偏爱的清晰特征，但未发现单一关联。在宿主根微生物群的组装过程中，对任一宿主的顺序接种都显示出强烈的优先作用，在该菌群中，已建立的群落可以抵抗后来者的入侵。但是，我们发现共生细菌对宿主的偏爱赋予了其原生宿主竞争优势。我们揭示了宿主的偏好在来自不同分类学组群的共生细菌中普遍存在，并且该特征与它们对立根相关社区的入侵直接相关。