Biogeography and community stability of leaf endophytic diazotrophs in mangrove Kandelia obovata

The leaf endosphere hosts diazotrophs vital for plant health and ecosystem resilience in saline environments. However, the geographic pattern and stability of the diazotrophic community in coastal salt marshes ecosystems are poorly understood. In this study, we examine the biogeographic distribution, assembly processes and community stability of leaf endophytic diazotrophs in the mangrove species Kandelia obovata across multiple regions in China. Our findings reveal that Rhizobiales are the most abundant in the diazotrophic communities. Community assembly is largely governed by stochastic processes, with dispersal limitations playing a dominant role. Soil nutrients emerge as the dominant factor influencing diazotroph composition, surpassing climatic variables and host traits. Notably, soil total sulfur (TS) serves as a key environmental factor shaping the diazotrophic community structure, with low TS environments supporting more stable microbial networks. These findings reveal ecological drivers and adaption strategies of endophytic diazotrophic communities in mangrove ecosystems, emphasizing the influence of nutrients dynamics in leaf endophytic microbial assembly under environmental changes.