Engineered biocontrol microbe induced gene silencing boosts its antifungal activity to Botrytis cinerea

Abstract

Gray mold caused by Botrytis cinerea poses severe threats to global horticultural production. Conventional chemical fungicides face mounting restrictions due to rising pathogen resistance and stringent food safety regulations, creating an urgent need for sustainable alternatives. RNA pesticides offer an eco-friendly alternative to chemical fungicides. However, the application of RNA pesticides faces challenges including double-stranded RNA (dsRNA) instability, delivery inefficiency, and high production costs. Here, we utilized an endophyte to produce dsRNA, enabling effective control of gray mold. The Beauveria bassiana strain QSE-F1 was proved as tomato endophyte and engineered to express dsRNA targeting BcMucin, an essential gene in B. cinerea and was validated as an effective RNA interference (RNAi) target. The engineered B. bassiana (Bb-dsMucin) produced and delivered dsRNA to achieve significant silencing of BcMucin at transcriptional and translational levels. The Bb-dsMucin strain showed superior antifungal activity and gray mold control efficacy compared with control strains. The combined use of conidia and fermentative broth of Bb-dsMucin attained optimal and lasting control efficacy. Our research establishes phyllosphere-derived Microbe-induced gene silencing (MIGS) as a promising biocontrol strategy for managing gray mold, and promotes the advancement of RNA pesticides technologies.