Seasonal Restructuring of the Rhizosphere Microbiome by Root Rot Pathogen and Identification of Antagonistic Microbes in Cunninghamia lanceolata

Aims Soil-borne pathogens severely damage Cunninghamia lanceolata through root rot, yet the temporal dynamics of its rhizosphere microbiome remain unclear. This study aimed to elucidate how Fusarium solani infection and seasonal variation jointly shape bacterial and fungal community structure. Methods We conducted a year-long field investigation in healthy and diseased plantations and analyzed seasonal shifts in rhizosphere microbial composition, soil physicochemical properties, and the prevalence of potential antagonistic taxa. Results Root rot induced season-dependent dysbiosis, selectively reshaping bacterial and fungal assemblages. Bacterial communities responded strongly to season–disease interactions, whereas fungal composition was primarily determined by tree health status. Spring and summer were key periods for disease-driven shifts. Healthy soils were enriched in beneficial taxa such as Acidobacteriae and Glomeromycetes, whereas diseased soils were dominated by Chalara and Trichoderma . Soil nutrients—particularly TOC, TN, and TK—played major roles in structuring microbial communities. Three antagonists ( Talaromyces liani , Chaetomium globosum , and Bacillus mojavensis ) exhibited strong biocontrol activity against F. solani . Conclusions Our findings reveal seasonally dynamic pathogen–microbiome interactions in the rhizosphere of C. lanceolata and provide ecological insights for developing sustainable, microbiome-based strategies for managing root rot disease.