Contribution of UDP-glycosyltransferases to triflumezopyrim tolerance regulated by microRNAs in Laodelphax striatellus.

Efficient detoxification is a key factor for the survival of pests exposed to insecticides. UDP-glycosyltransferase (UGT) is a superfamily of phase II detoxifying enzymes, which plays an important role in xenobiotics metabolism including insecticides. As a key post-transcriptional regulator, microRNA (miRNA) has been shown to regulate insecticide resistance by modulating the expression of detoxification enzyme-encoding genes in insects. In this study, 21 UGT genes were identified in small brown planthopper (SBPH), Laodelphax striatellus, of which 16 genes belonged to the UGT386 family, indicating that there were obvious gene duplication. UGT activity determination and synergism bioassay following LD dose of triflumezopyrim exposure demonstrated that UGT genes played a key role in triflumezopyrim tolerance. Then, UGT385A1, UGT386G1 and UGT386J1 were significantly overexpressed more than two-fold after triflumezopyrim treatment. However, only inhibiting the expression of UGT386G1 and UGT386J1 enhanced the sensitivity of SBPH to triflumezopyrim. Furthermore, bioinformatics tools were used to predict the potential miRNAs which regulated UGT386G1 and UGT386J1. The downstream regulation of the target was evaluated by injection of agomir-miRNA, and the interaction between miRNAs and UGT genes was verified by dual luciferase reporter assay. These findings confirmed that miR-281-5p and PC-3p-4042_506 participated in triflumezopyrim tolerance in SBPH through post-transcriptional regulation of UGT386G1 and UGT386J1, respectively. This finding provides functional evidence for UGT gene-mediated detoxification of triflumezopyrim. It also provides valuable insights for further research and the development of strategies to mitigate the emergence of triflumezopyrim resistance in insects.