Antagonistic activity of a novel antifungalmycin N2 from Streptomyces sp. N2 and its biocontrol efficacy against Rhizoctonia solani.

Antifungalmycin N2 (3-methyl-3,5-amino-4-vinyl-2-pyrone, C6H7O2N) is a novel bioactive substance produced by Streptomyces sp. N2. In the present work, the antagonistic activity of antifungalmycin N2 and its biocontrol efficacy on Rhizoctonia solani were carried out to evaluate its potential as a biocontrol agent against fungal plant diseases. By using potato dextrose agar (PDA) media for in vitro cultivation of phytopathogenic fungi, the results showed that antifungalmycin N2 not only displayed broad-spectrum antifungal activities against various plant pathogenic fungi, but also had a strong antagonism to the sclerotial germination of R. solani. In a detached leaf assay, it was found that antifungalmycin N2 could effectively protect the rice leaves form the infection of R. solani, resulting in a significantly reduced sheath blight severity on the surfaces of rice leaves. In the pot experiments, the results also revealed that significantly lower sheath blight infections occurred in the tissues of the treated rice plants, which further confirmed that antifungalmycin N2 had a favorable biocontrol efficacy on rice sheath blight. In conclusion, the above results indicated that the novel antifungalmycin N2 was one of promising biocontrol agents for plant disease control.