Spatial structuring of bacterial communities found on individual Ginkgo biloba trees

Plant-associated microorganisms affect the health of their hosts in myriad ways, yet the distribution of these organisms within individual plants remains poorly understood. To address this knowledge gap, we assessed the spatial variability in bacterial community diversity and composition found on and in aboveground tissues of individual Ginkgo biloba trees. We sampled bacterial communities from more than 100 locations per tree, including leaf, branch, and trunk samples, and used high-throughput sequencing of the 16S rRNA gene to determine the diversity and composition of these communities.Bacterial community structure differed strongly between bark and leaf samples, with bark samples harboring much greater bacterial diversity and a distinct community composition than leaves. In addition, we observed distinct spatial patterns in bacterial diversity and community composition across individual trees within sample types that were generally related to the samples proximity to the exterior of the tree. These findings suggest bacterial community structure within trees is highly variable but also predictable. Moreover, this work highlights the importance of carefully considering plant spatial structure when characterizing the microbial communities associated with plants in order to avoid biases incurred through this spatial heterogeneity.