This study aimed to investigate the inhibitory effects and mechanisms of essential oil and its endophytic fungi of Camphora bodinieri with citral chemotype (CBCC) against Rhizoctonia solani, the causal agent of rice sheath blight. The antifungal activity was assessed by measuring the inhibition rate at various concentrations. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe ultrastructural changes in the pathogen. For the CBCC bodinieri essential oil treatment group, the MIC was 1.0 μL/mL, and the inhibition rate reached 100%, showing a concentration-dependent effect (0.0625–1.0 μL/mL, inhibition rate 29.02–100%). Electron microscopy showed that the essential oil caused severe damage to hyphal cell membranes, cytoplasmic agglutination, and organelle disintegration, whereas the endophytic fungi caused only local shrinkage and partial deformation. Both the CBCC essential oil and the endophytic fungi exhibit antifungal activity. They are promising candidates for the biological control of rice sheath blight and have potential for development as biofungicides.

To investigate the influence of seasonal dynamics on the endophytic fungal community of Camphora bodinieri with citral chemotype, we employed standardized sampling and high-throughput sequencing to analyze the diversity, composition, and structure of endophytic fungi across different seasons. A total of 1825 Amplicon Sequence Variants (ASVs) were obtained, belonging to 12 phyla, 43 classes, 104 orders, 239 families, 449 genera, and 663 species. Among them, 23 ASVs were shared across all four seasons, suggesting the presence of a core fungal community. The number of season-specific ASVs was highest in autumn (730), followed by summer (336), spring (325), and winter (202). The results showed that season significantly affected the Shannon (F_3,9 = 5.927, p = 0.016) and Simpson (F_3,9 = 4.892, p = 0.026) indices, with the diversity and species richness of endophytic fungi being highest in autumn and lowest in winter. Across different tissues, the similarity of endophytic fungal communities between leaves and stems was comparatively higher than that with roots. Furthermore, different fungal taxa exhibited differential distribution patterns along temperature–moisture gradients. This study explored the seasonal diversity of endophytic fungi in C. bodinieri with citral chemotype, providing a theoretical basis for understanding host–endophyte interactions.