Host genotype shapes the foliar fungal microbiome of Balsam poplar

Foliar fungal communities on plants are hyperdiverse and ubiquitous. While fungal endophytes in grasses may increase host fitness, their ecological roles in trees are much less understood. We performed a high-resolution analysis to provide an assessment of the potential effects of host genetic makeup over leaf associated fungal communities in a tree species. We investigated whether the genetic makeup of the host influences community structure of foliar fungi. We sampled leaves from genotyped balsam poplars from across the range grown in a common garden, and applied 454 amplicon sequencing to characterize foliar fungal communities. We found diverse fungal communities in the poplar leaves. Our data suggests that host genotypes have a structuring effect on the composition of these communities. The observed patterns may be explained by a filtering mechanism by which the trees “recruit” fungal strains from the environment. Alternatively, hosts may be systemically infected by fungi, and preserve characteristic communities even after two clonal reproductions. Our findings suggest an intimate, non-incidental relationship between tree genotypes and their foliar fungi. As balsam poplar colonized its current range within the past 18,000 years, our study suggests that foliar fungal-plant relationships may form within short geological timeframes.