International Journal of Biological Macromolecules, 2024,https:// doi: 10.1016/j.ijbiomac.2023.128654  

Abstract

The bacterium  Bacillus thuringiensis  (Bt) is the most economically successful biopesticide to date, and Bt insecticidal proteins are produced in transgenic crops for pest control. However, relevant details in the Bt-mediated killing process remain undefined. In our previous research, we observed reduced larval susceptibility to Bt Cry1Ca in  Chilo suppressalis , a major rice pest in China, after gut microbiota elimination. Here, we tested the hypothesis that gut microbiota, particularly abundant  Enterococcus  spp., influences  C. suppressalis  susceptibility to Cry1Ca. We isolated and identified four  Enterococcus  spp. from  C. suppressalis  gut microbiota and evaluated their impact on Cry1Ca toxicity. Among the four  Enterococcus  spp. identified, three of them ( E. casseliflavus, E. faecalis , and  E. mundtii ) dramatically increased larval mortality when introduced in axenic  C. suppressalis  challenged with Cry1Ca. Gut epithelial damage by Cry1Ca promoted the translocation of  Enterococcus  spp. from the gut lumen into the hemocoel, where they proliferated and induced larval melanization and hemocyte apoptosis. Our combined findings demonstrate that the presence of specific gut microbiota can greatly affect susceptibility to Cry1Ca through melanization and apoptosis of hemocytes. Better understanding of the Bt intoxication process guides the development of bio-enhancers for Bt-based microbial biopesticides and potential improvement of transgenic crops.

International Journal of Biological Macromolecules,IF=8.2

https://pubmed.ncbi.nlm.nih.gov/38065453/