Comparative Transcriptome Analysis of Bt Resistant and Susceptible Strains in Ostrinia furnacalis (Guenée) (Lepidoptera: Crambidae)

Abstract

The evolution of target pest population resistance to Bt toxins is the most relevant threat to the sustainability of Bt technology, thus it is necessary to clarify insect resistance mechanisms. Firstly, the resistance level of Asian corn borer was determined by bioassay. After 28 generations selection in the lab, the Cry1Ie-resistant strain (ACB-IeR) developed more than 862-fold resistance to Cry1Ie, and the Cry1F-resistant strain (ACB-FR) developed 961-fold resistance to Cry1F. The results show that long-term exposure to Bt toxins can lead to resistance. Then, we compared the differential expression genes (DEGs) of ACB-FR and ACB-IeR with susceptible strain (ACB-BtS), and analyzed GO function and KEGG pathway through transcriptome sequencing. The comparison showed that in Bt-resistant strains, many genes have a significant down-regulated trend. Several Bt-resistance candidate genes were differentially expressed in both resistant strains. Furthermore, the DEGs were verified by RT-qPCR and showed similar trend. These results provide candidate genes for further research on the Bt resistance mechanism.

Hemocyte response to treatment of susceptible and resistant Asian corn borer (Ostrinia furnacalis) larvae with Cry1F toxin from Bacillus thuringiensis

“…Transcriptomic and proteomic analyses in ACB resistant to Cry1Ah detected down-regulation of putative receptor and detoxification genes, while anti-stress genes were up-regulated ( 24 ). Similar studies in ACB resistant to Cry1Ie or Cry1F detected down-regulation of multiple genes when compared to susceptible insects ( 25 ). Notably, the Cry-1F resistant ACB-FR strain presented up-regulation of glutathione-S-transferase, which was not detected in Cry1Ie-resistant ACB.…”