Tree type-specific endophytic bacterial assembly and function in senescing leaves and needles in temperate forests of Central Europe

BACKGROUND: Leaves and needles are pivotal plant tissues in regulating carbon input, nutrient uptake, and biogeochemical cycling within ecosystems. However, the ecological strategy of broadleaved and coniferous tree species affecting the endophytic colonization of leaf/needle for enabling a nutrient release of subsequent litter is not fully known. The bacterial community assembly, functions, and interactions (summarized as attributes) inhabiting senescing leaves and needles in eleven common tree species of Central European forests were investigated using next generation sequencing. RESULTS: Endophytic bacterial attributes varied significantly among tree species and between tree types (broadleaved and coniferous trees). Deterministic processes (nitrogen (N) related factors) governed the endophytic bacterial community assemblages in broadleaved tree species, which were dominated by ureolytic bacteria that potentially caused the increase in inorganic N. In turn, stochasticity (homogenizing dispersal and dispersal limitation) predominantly controlled the community assembly of bacteria inhabiting in needles. Compared with broadleaved, coniferous trees exhibited both more diverse bacterial taxa enlarging the capacity to cope with changing environmental factors. CONCLUSIONS: Our results reveal the endophytic colonization patterns that initiate litter decomposition during leaf and needle maturation and demonstrate variations between tree types.