The aerial surface of plant leaf, known as phyllosphere, provides a ubiquitous habitat for numerous microorganisms including bacteria and fungi. Recent studies on phyllosphere microbiomes highlighted potential roles of phyllosphere microbes for plants functional traits as well as ecosystem functioning, but drivers of the diversity, composition, and function of the phyllosphere microbial communities are still poorly understood. In this study, we collected microbes from the leaf surfaces from subtropical forests on ten islands in the Thousand-Island Lake, China. We sampled shade leaves from 20 tree species on each island and collected microbial cells from the leaf surfaces using polyester swabs. Bacterial and fungi community structures were quantified using high-throughput sequencing. The functional potential of microbial communities was quantified using Biolog EcoPlates. We investigated drivers of variations in diversity and composition of phyllosphere microbial communities by studying the influence of islands and host trees identity. Our objectives are to (1) examine the influence of islands and host plants on species and functional diversity of phyllosphere microbial communities, (2) compare the magnitude of inter-island variations and interspecific variations in phyllosphere microbial structure, and (3) test for the relative importance of spatial distance, difference in island area, and host tree identity on phylogenetic turnover and functional turnover of phyllosphere microbial communities.
Results/Conclusions
We report three key findings. First, both island and host tree identity significantly influenced diversity and function of phyllosphere microbial communities. Bacterial diversity, not fungal diversity, significantly increased with island area. Second, both island and host tree identity significantly influenced leaf bacterial and fungal community structure, with host tree identity explaining more variation (11.6% and 16.5 for bacteria and fungi, respectively) than island identity (9.4% and 12.9% for bacteria and fungi, respectively). Third, the phylogenetic turnover of bacterial and fungal communities was related to host tree identity rather than spatial distance and difference in island size. Host tree identity also affected functional turnover of leaf microbial communities both directly and through affecting bacteria turnover. Our study emphasized the importance of host plant identity as the main driver of diversity, composition, and function of phyllosphere microbial communities.