Leaf nutrients regulate phyllosphere microbial dynamics in rubber trees.

Mechanisms underlying the assembly and succession of phyllosphere microbiota in rubber plantations are crucial for understanding ecosystem health and functionality, yet poorly understood. In this study, high-throughput sequencing was used to analyze the diversity, assembly mechanisms, and potential sources of phyllosphere microbial communities at developmental stages. Key findings include: (1) Epiphytic and endophytic bacterial diversity peaked at the budding stage, then decreased and subsequently showed a gradual increase again toward the senescence stage, primarily driven by leaf nitrogen (N), phosphorus (P), and potassium (K). However, epiphytic and endophytic fungal diversity was significantly regulated by leaf N and P. (2) Assembly processes exhibited niche differentiation: the assembly of epiphytic bacteria during the color-changing and stable stages was dominated by stochastic processes, while deterministic regulation prevailed in other stages and in endophytic communities. Both assembly and network complexity were driven by leaf N and K dynamics. Fungal network complexity and deterministic regulation, in both epiphytic and endophytic niches, were promoted by leaf N and P during early stages but gradually weakened thereafter. (3) Active material exchange occurred between epiphytic and endophytic niches, and below-ground niches contributed more significantly to the fungal community. Overall, our results underscores that leaf nutrients modulate the diversity, assembly, and resultant compositional landscape of phyllosphere microorganisms at different developmental stages. These insights contribute to deepening the fundamental understanding of plant-microbial symbiosis and inform strategies for the cultivation of rubber trees.