Interference with sexual mating of Sporisorium scitamineum by verrucarin A isolated from Paramyrothecium sp

Summary

Scientists discovered a fungus from moss that produces a natural compound called verrucarin A, which stops sugarcane smut disease by preventing the sexual mating of its fungal spores. This prevents the disease from developing without harming the sugarcane plants. In greenhouse tests, this natural biocontrol agent reduced disease occurrence by nearly half compared to untreated plants, offering a safe alternative to chemical pesticides for protecting sugarcane crops.

Background

Sugarcane smut, caused by Sporisorium scitamineum, is a major global threat to sugarcane production. The disease requires sexual mating between haploid spores to produce diploid mycelia that initiate infection. Current control strategies using resistant varieties and chemical methods have limitations due to physiological diversity and environmental concerns.

Objective

To isolate and characterize a biocontrol fungal strain that inhibits sexual mating of S. scitamineum and identify its active antimicrobial compound for potential application in sugarcane smut management.

Results

Verrucarin A (Ver-A) was identified as the active compound responsible for inhibiting S. scitamineum sexual mating with a minimum inhibitory concentration of 8 μg/mL. Ver-A disrupted mating by modulating expression of genes at loci a and b without directly killing haploid spores. Greenhouse experiments demonstrated that P-6 fermentation products reduced smut disease incidence from 80% to 37% with no phytotoxicity.

Conclusion

Verrucarin A from Paramyrothecium sp. strain P-6 effectively inhibits sugarcane smut by interfering with the sexual mating process. These findings establish P-6 as a promising biocontrol agent for sustainable management of sugarcane smut disease and offer a safe, eco-friendly alternative to chemical control methods.
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