Transcriptomic investigation reveals a physiological mechanism for Beauveria bassiana to survive under linoleic acid stress

In integrated pest management program (IPM), the compatibility of mycoinsecti-cides with bioactive fungicides [e.g., unsaturated fatty acids (UFAs)] has attracted more and more attention; however, the mechanisms underlying fungal resistance to UFAs remain largely unknown. In this study, Beauveria bassiana, an entomopa-thogenic fungus, was used to explore fungal responses to linoleic acid (LA). Genome-wide expression revealed the transcriptomic responses of fungal cells to LA in a stress-intensity-dependent manner. Enrichment analyses indicated that the up-regulated differentially expressed genes (DEGs) are associated with the metabolism of lipid and fatty acids. Notably, a lipid-droplet protein (BbLar1) maintains the intracellular homeostasis of fatty acids and is crucial to fungal tolerance to LA stress, which significantly contributes to fungal compati-bility with UFAs. Additionally, BbLar1 links the lipid droplets to global expression profiles in B. bassiana under LA stress. Our investigations provide an initial frame-work for improving the efficacy of insect pathogenic fungi in practical application.