Dual RNA Sequencing of Beauveria bassiana-Infected Spodoptera frugiperda Reveals a Fungal Protease with Entomopathogenic and Antiphytopathogenic Activities

Insect pests and phytopathogens significantlyimpact crop yieldand quality. The fall armyworm (FAW) Spodoptera frugiperda and the phytopathogen Fusarium graminearum cause substantial economic losses in crops like barley and wheat.However, the entomopathogen Beauveria bassiana shows limited efficacy against FAW, and its antiphytopathogenicactivities against F. graminearum remainunclear. Here, dual RNA sequencing was performed to identify differentiallyexpressed genes in B. bassiana-infectedFAW larvae. We found that the BbAorsin gene was significantlyupregulated at 36 and 48 h post-infection. BbAorsin encodes a serine-carboxyl protease and is mainly expressed in blastosporesand hyphae. Overexpression of BbAorsin in B. bassiana ARSEF2860 enhanced virulence against Galleria mellonella and FAW larvae and inhibited F. graminearum growth. The recombinant BbAorsin proteininduced apoptosis and necrosis in FAW hemocytes and inhibited F. graminearum spore germination. These findingsshed light on transcriptomic mechanisms governing insect-pathogeninteractions, which could aid in developing dual-functional entomopathogensand anti-phytopathogens.