In vitro Expression of Laodelphax striatellus CYP426A1 and Its Catalytic Role to Degrade Insecticide

Over-expression of cytochrome P450 monooxygenases (P450s) genes are regularly associated with insecticide resistance in resistant insects. The CYP426A1 gene, which had not previously been reported as over-expressed in L. striatellus strains, was studied to determine its catalytic role in degrading insecticides. Firstly, CYP426A1 gene was recombinantly expressed in Sf9 cells and the expressed target protein was confirmed by SDS-PAGE. Subsequently, CYP426A1 protein was confirmed as a functional enzyme through CO-difference spectra analysis. Additionally, CYP426A1 favorably metabolize traditional model probe substrates viz p-nitroanisole, ethoxycoumarin and ethoxyresorufin to confirm its catalytic activity. Insecticides from various group were incubated with recombinant CYP426A1 to confirm its catalytic activity in degrading insecticides. The results demonstrated that only fipronil was degraded by CYP426A1, with no enzyme-catalyzed degradation observed for imidacloprid, deltamethrin, and chlorpyrifos. Thus, CYP426A1 contributes to the development of insecticide resistance in L. striatellus, despite not being previously over-expressed in resistant strains.