Transcriptomic analysis reveals the potential antioxidant pathways regulated by multiprotein bridging factor 1 (BbMBF1) in the fungal entomopathogen Beauveria bassiana

Resistance to oxidative stress is crucial to environmental fitness and potency of the fungal entomopathogen Beauveria bassiana. Multiprotein bridging factor 1 (BbMBF1), an evolutionarily conserved transcriptional cofactor, plays an important role in development and stress tolerance of eukaryotic organisms. It has been established that the B. bassiana homologue (BbMBF1) contributes to the fungal response to menadione stress under lower nutritional conditions. The present study indicated that rich nutrient reduces fungal sensitivity to menadione stress, but further confirmed that the BbMBF1 is also required for fungal tolerance to oxidation under rich nutritional conditions. To explore the down-stream targets regulated by BbMBF1 under menadione stress, a comparative trancriptome was performed on the wild type and the Delta BbMBF1 mutant strains. Transcriptomic analysis showed that the oxidation-response genes regulated by BbMBF1 were significantly enriched in the functional catalogues of metabolism, cell rescue and transportation. Moreover, bioinformatic analysis predicted a putative motif which distributed mainly over the promoters of genes associated with metabolism and detoxification. Conclusively, these results indicate that BbMBF1 contributes to B. bassiana response to oxidative stress by mediating the potential transcription factors regulating pathway of metabolism and detoxification. These findings highlight the potential antioxidant strategies in the fungal entomopathogens, and provide the new clues/targets for improving potency of entomopathogenic fungi by molecular manipulation.