Interference with sexual mating of <i>Sporisorium scitamineum</i> by verrucarin A isolated from <i>Paramyrothecium</i> sp.

Sugarcane smut, caused by <i>Sporisorium scitamineum</i>, poses a significant global threat, leading to substantial economic losses. The pathogenic process involves haploid spores engaging in sexual mating to produce diploid mycelia, which then initiates the disease by penetrating sugarcane tissues. Targeting the mating process has thus emerged as the Achilles' heel in controlling sugarcane smut. In this study, we isolated a fungus designated as P-6 from a bryophyte, which impeded the mycelia formation of <i>S. scitamineum</i>. Phylogenetic and morphological analyses classified the strain P-6 within the genus <i>Paramyrothecum</i>. Through ethyl acetate extraction, subsequent separation, and nuclear magnetic resonance (NMR) analysis, we identified the active compound responsible for inhibiting the mating process as verrucarin A (Ver-A). Specifically, Ver-A inhibited the sexual mating of <i>S. scitamineum</i> by modulating the gene expression of loci <i>a</i> and <i>b</i>. Greenhouse pot experiments underscored the efficacy of strain P-6's fermentation products in reducing the incidence of sugarcane smut. These findings lay a robust groundwork for the development and application of P-6 as a novel biocontrol strain against sugarcane smut.