The Mechanism of Antifungal Action of a New Polyene Macrolide Antibiotic Antifungalmycin 702 from Streptomyces padanus JAU4234 on the Rice Sheath Blight Pathogen Rhizoctonia solani

Antifungalmycin 702, a new polyene macrolide antibiotic produced by Streptomyces padanus JAU4234, has a broad antifungal activity and may have potential future agricultural and/or clinical applications. However, the mechanism of antifungal action of antifungalmycin 702 remains unknown. Antifungalmycin 702 strongly inhibited mycelial growth and sclerotia formation/germination of Rhizoctonia solani. When treated with antifungalmycin 702, the hyphae morphology of R . solani became more irregular. The membrane and the cellular organelles were disrupted and there were many vacuoles in the cellular space. The lesion in the plasma membrane was detected through the increase of membrane permeability, lipid peroxidation and leakage of cell constituents. In summary, antifungalmycin 702 may exert its antifungal activity against R . solani by changing the structure of cell membranes and the cytoskeleton and interacting with the organelles.