The phyllosphere bacterial communities of Mediterranean plants in summer and winter

We use next generation sequencing (NGS) to survey the composition of bacterial communities on the phyllosphere of nine native perennial species that co-occur in a Mediterranean ecosystem, at Halkidiki, Greece. In parallel, we survey the composition of the airborne microbial inoculum. Trying to detect the main drivers of the epiphytic community composition, we examine the airborne and epiphytic communities during summer and winter, the two highly contrasting seasons in this environment. The bacterial diversity was higher in summer. Among the epiphytic bacteria, Proteobacteria is the prominent phylum, followed by Actinobacteria. There are striking differences among the epiphytic bacterial communities and the airborne inoculum. The major driver differentiating the structure of the bacterial epiphytic community in the Mediterranean environment is season. Notably, the prominence of season against plant species derived after studying co-occurring taxa that differ considerably in their leaf features. The summer epiphytic community is characterized by higher taxonomic richness and higher connectivity than the winter one with the increased richness occurring at the expense of the dominant Proteobacteria.