Antifungal Activity of Leaf Essential Oil and Its Endophytic Fungi of Camphora bodinieri with Citral Chemotype Against Rhizoctonia solani

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.