In vivo transcriptomic analysis of Beauveria bassiana reveals differences in infection strategies in Galleria mellonella and Plutella xylostella.

BACKGROUND: Insect pests have evolved various defense mechanisms to combat fungal infection, fungi have developed multiple strategies to overcome the immune defense responses of insect. However, transcriptomic analysis of fungal strategies for infecting different pests has not been reported.

RESULTS: Transcriptomic profiling of Beauveria bassiana was performed at 12, 24 and 48 h after infecting Galleria mellonella and Plutella xylostella, and 540, 847 and 932 differential expressed genes were detected, respectively. Functional categorization showed that most of these genes are involved in the ribosome, nitrogen metabolism and oxidative phosphorylation pathways. Thirty-one differentially expressed virulence genes (including genes involved in adhesion, degradation, host colonization and killing and secondary metabolism) were found, suggesting that different molecular mechanisms were used by the fungus during infection of the different pests, which was further confirmed by disrupting creA and fkh2. Virulence assay results showed that ΔcreA and Δfkh2 strains of B. bassiana had distinct fold changes in their LT50 values (compared with the control stains) during their infection of G. mellonella (ΔcreA: 1.38-fold > Δfkh2: 1.18-fold) and P. xylostella (ΔcreA: 1.44-fold < Δfkh2: 2.25-fold). During infection progress, creA was expressed at higher levels during the infection of G. mellonella compared to P. xylostella, while fkh2 showed the opposite expression pattern, demonstrated that creA and Fkh2 play different roles in B. bassiana during the infection of G. mellonella and P. xylostella.

CONCLUSION: These findings demonstrate that B. bassiana regulates different genes to infect different insects, advancing knowledge of the molecular mechanisms of Beauveria-pest interactions. This article is protected by copyright. All rights reserved.