Microbial insights into the survival adaptation of the endemic orchid Corybas fanjingshanensis in a "sky island" habitat.

Understanding the microbiological basis of species adaptation is crucial for effective conservation. This study investigates the endangered, narrow-endemic orchid Corybas fanjingshanensis and its symbiotic moss substrate in a "sky island" habitat, using high-throughput sequencing to analyze microbial communities and their potential roles in host survival. Results reveal significant divergence between endophytic and environmental microbiomes. Endophytic bacterial diversity was lower, but dominance was higher than in the moss substrate. We identified 65 core bacterial and 18 core fungal genera, predominantly enriched in nutrient acquisition and stress tolerance functions. Five key bacterial taxa, including Vicinamibacteraceae and Mucilaginibacter, were highlighted as potential conservation targets. The C. fanjingshanensis-moss symbiotic network exhibited strong positive interactions and high modularity, forming tight functional clusters likely enhancing environmental stress resistance. While bacterial functional genes remained stable across communities, fungal nutritional strategies were influenced by environmental heterogeneity. We propose conservation measures, including microbial transplantation to rebuild host-microbe symbioses, selective amplification of core taxa, and a holistic framework integrating habitat integrity with long-term microbial monitoring. This study offers insights into the survival strategies of narrow-endemic plants and advances microbiome-based orchid conservation, shifting the paradigm from habitat simulation to microbial network restoration.IMPORTANCEUsing Corybas fanjingshanensis, a critically endangered species with an extremely limited distribution, as the research subject, high-throughput sequencing technology was employed to investigate its survival adaptations from a microbial perspective within the unique "sky island" habitat. The findings provide a reference for microbiome-based conservation of endangered narrow-endemic species and offer insights into plant habitat reconstruction.