Turnover of endophytic microbial communities under environmental change
Within-host microbial communities are determined by processes spanning an array of spatial scales, including interactions among microbes within and among individual hosts and across regional environments. Thus, microbial communities span and feed back across spatial, temporal, and taxonomic boundaries and are set on a backdrop of local and regional abiotic context. We manipulated nutrient supply and food web composition at four grassland sites spanning the central US and, using Illumina sequencing, examined the scales of turnover in the endophytic fungal community within individuals of a widespread prairie grass species, Andropogon gerardii.
Endophytic microbial communities in our focal host were composed of hundreds of fungal taxa, which were mostly ascomycetes. Phylogenetic identity of these OTUs suggests the endophytic community is composed of fungal groups including those that likely act as pathogens, beneficial endophytes, neutral endophytes, and latent saprophytes. We found that microbial communities within host individuals of our focal species varied among sites across the region, among leaves on a single plant, and in response to experimental nutrient supply. Taken together, our results suggest that endophytic microbial communities are only partially a function of local host richness and density. Developing an understanding of plant microbiomes will require empirical data and models that explicitly incorporate the nested spatial structure of the endophytic community.