BACKGROUND The phyllosphere is an important microbial habitat, but our understanding of how plant hosts drive the composition of their associated leaf microbial communities and whether taxonomic associations between plants and phyllosphere microbes represent adaptive matching remains limited. In this study, we quantify bacterial functional diversity in the phyllosphere of 17 tree species in a diverse neotropical forest using metagenomic shotgun sequencing. We ask how hosts drive the functional composition of phyllosphere communities and their turnover across tree species, using host functional traits and phylogeny. RESULTS Neotropical tree phyllosphere communities are dominated by functions related to the metabolism of carbohydrates, amino acids, and energy acquisition, along with environmental signalling pathways involved in membrane transport. While most functional variation was observed within communities, there is non-random assembly of microbial functions across host species possessing different leaf traits. Metabolic functions related to biosynthesis and degradation of secondary compounds, along with signal transduction and cell-cell adhesion, were particularly important in driving the match between microbial functions and host traits. These microbial functions were also evolutionarily conserved across the host phylogeny. CONCLUSIONS Functional profiling based on metagenomic shotgun sequencing offers evidence for the presence of a core functional microbiota across phyllosphere communities of neotropical trees. While functional turnover across phyllosphere communities is relatively small, the association between microbial functions and leaf trait gradients among host species supports a significant role for plant hosts as selective filters on phyllosphere community assembly. This interpretation is supported by the presence of phylogenetic signal for the microbial traits driving inter-community variation across the host phylogeny. Taken together, our results suggest that there is adaptive matching between phyllosphere microbes and their plant hosts. Video abstract.

中文翻译：

---

新热带森林中的叶环细菌与其树宿主之间的适应性匹配。

背景技术叶环是重要的微生物栖息地，但是我们对植物宿主如何驱动其相关叶微生物群落组成以及植物与叶球微生物之间的分类学关联是否代表适应性匹配的理解仍然有限。在这项研究中，我们使用宏基因组shot弹枪测序技术来量化新热带森林中17种树种的叶层细菌功能多样性。我们问宿主如何利用宿主的功能性状和系统发育来驱动叶球群落的功能组成及其跨树种的更新。结果新热带树的叶圈社区以与碳水化合物，氨基酸代谢和能量获取有关的功能以及与膜运输有关的环境信号通路为主。尽管在群落中观察到大多数功能变异，但具有不同叶片性状的宿主物种之间的微生物功能却非随机聚集。与次级化合物的生物合成和降解有关的代谢功能，以及信号转导和细胞间粘附，对于推动微生物功能与宿主性状之间的匹配特别重要。这些微生物功能在整个宿主系统发育上也是进化保守的。结论基于宏基因组shot弹枪测序的功能分析为新热带树木的叶球群落中存在核心功能微生物群提供了证据。虽然整个叶圈社区的功能更新率相对较小，寄主物种之间的微生物功能与叶片性状梯度之间的关联支持了植物寄主作为叶球群落组装的选择性过滤器的重要作用。这种解释得到了微生物发生的系统发育信号的支持，该微生物特征驱动整个宿主系统发生群落间变异。两者合计，我们的结果表明，叶球微生物与其植物宿主之间存在适应性匹配。录像摘要。