Study on the Rhizosphere Soil Microbial Diversity of Five Common Orchidaceae Species in the Transitional Zone Between Warm Temperate and Subtropical Regions

Orchidaceae is among the most diverse and widely distributed families of angiosperms, with significant ecological, ornamental, and medicinal value. However, the structure, function, and environmental associations of rhizosphere soil bacterial communities associated with Orchidaceae remain poorly characterized. This study selected five common Orchidaceae species in the transitional zone between the warm temperate and subtropical regions of China (Changnienia amoena, Cypripedium macranthos, Cremastra appendiculata, Cymbidium faberi, and Gastrodia elata). Using high-throughput sequencing technology, we characterized the bacterial diversity of the rhizosphere soil associated with these species and investigated their relationships with soil physicochemical properties. The results show significant differences in the structure of rhizosphere soil bacterial communities among the five Orchidaceae species. The principal environmental factors influencing these communities differ across species. Fermentation functional bacteria dominate the rhizosphere bacterial communities. The community assembly processes of specialized and generalized species are governed by deterministic and stochastic processes, respectively, indicating complex ecological mechanisms. This study clarifies the structural characteristics, functional differentiation, and environmental response mechanisms of rhizosphere soil bacterial communities across Orchidaceae species. It provides a theoretical foundation for the conservation and sustainable utilization of Orchidaceae from a microbiological perspective.