Host identity determines the bacterial and fungal community and network structures in the phyllosphere of plant species in a temperate steppe

Elucidating the plant-microbiome network is of importance in understanding species coexistence of natural ecosystems. Phyllosphere, which is the aerial parts of terrestrial plants, is inhabited by diverse microbes. However, few studies have focused on phyllosphere microbiome and plant-microbiome network in temperate grasslands. In this study, we explored the diversity, community structure, and network architecture of phyllosphere bacteria and fungi in 19 plant species native to the temperate grassland in Inner Mongolia, China. We obtained 3,313 and 758 phyllosphere bacterial and fungal OTUs, and found that the bacterial community was dominated by Proteobacteria, Actinobacteriota and Firmicutes. The fungal community was dominated by Ascomycota and Basidiomycota. Plant identity exerted significant impacts on α-diversities of both bacterial and fungal communities. The composition of bacterial and fungal communities differed among plant species. Plant identity had a greater effect on fungal than on bacterial communities. Both bacterial and fungal network structures were characterized by specialized and modular, lowly connected and no nested properties. The plant-fungal network had a high level of specification, modularity, antinestedness and connectance compared to the plant-bacterial network. Our results suggest more intimate relationships between plants and phyllosphere fungi than between plants and phyllosphere bacteria, and that the phyllosphere fungal community is more resistant to environmental disturbance than the phyllosphere bacterial community in the temperate grassland ecosystem. These findings may contribute to our understanding of the mechanisms by which species coexist and community stabilizes in the grassland ecosystems.