Year-round dynamics of phyllosphere bacterial communities on leaves, twigs and buds of five tree species

The composition of phyllosphere bacterial communities is influenced by geographic location, host plant genotype, ambient air quality and seasonal variation. Yet, we know little about the temporal variation in leaf bacterial communities and its relation with bacterial communities on twigs and inside buds. In this observational study, we explored how bacterial communities on leaves and twigs of different plant host species evolve through the growing season. To do so, we determined the taxonomic bacterial composition of three phyllosphere compartments for five tree species in a common-garden setting from the inside of leaf buds over leaf emergence until the leaves are shed. The phyllosphere bacterial communities on leaves underwent substantial changes through the growing season, in contrast to the bacterial community on the twigs which remained fairly stable through the growing season. Over time, the twig and leaf bacterial communities became more alike. In contrast to the twigs, the communities in the buds did not resemble the microbial community of the leaves in the beginning of the growing season more than later-on. Lastly, sampling time, host tree species and phyllosphere compartment were important drivers of the diversity and community composition of phyllosphere bacterial communities.