Habitat Characteristics and Root Mycobiome Diversity of Cypripedium shanxiense S. C. Chen in the Changbai Mountains

Cypripedium shanxiense S. C. Chen has high ornamental value; it relies on specific habitats and fungi. Wild C. shanxiense populations need urgent conservation because they are declining rapidly. This study investigated three wild C. shanxiense populations under different canopy densities in the Changbai Mountains, analyzing habitat characteristics and plant morphology. Tissue isolation methods, molecular identification techniques, and metagenomic approaches were applied separately to purify root-colonizing fungi and to investigate the composition and functions of rhizosphere fungi, thereby revealing the diversity of root mycobiome in C. shanxiense. Results revealed that C. shanxiense achieved the best growth when the canopy density was 85.29%, and the lowest growth was under 96.13% canopy density. Soil phosphorus and potassium contents reached their highest levels under 69.33% canopy density, while soil nitrogen and organic matter contents peaked at 85.29%. Soil organic matter and available nitrogen constitute the core nutrient factors for the growth of C. shanxiense. A total of 16 fungal strains were mainly enriched in the roots, all belonging to Ascomycota. Including numerous growth-promoting fungi and pathogenic fungi. The rhizosphere fungi were mainly enriched with Basidiomycota and Ascomycota. Functional genes related to replication, recombination, and repair, and Glycoside Hydrolases. This study clarifies the optimal growth conditions of this species and the dominant rhizosphere and root fungi, providing a scientific basis for the ecological restoration and conservation of rare species.