LAUSR

Abstract In insects, glutathione S-transferases (GSTs) play essential roles in the detoxification of xenobiotic toxins and elimination of oxidative stress induced by toxic compounds. In the present study, a delta class GST gene (AiGSTd) was identified and characterized in the black cutworm, Agrotis ipsilon (Lepidoptera: Noctuidae). The deduced protein sequence of AiGSTd contained highly conserved features of GST enzymes and shared high identities with its orthologs from other lepidopteran species. Recombinant AiGSTD protein was expressed in Escherichia coli and purified. The protein displayed the GSH-dependent conjugating activity toward the substrate 1-chloro-2,4-dinitrobenzene (CDNB). Moreover, AiGSTD had the ability to protect DNA from oxidative damage, and the E. coli cells overexpressing AiGSTD showed long-term resistance to oxidative stress. The AiGSTd transcripts were most abundant in the larval midgut. Exposure to chlorpyrifos and lambda-cyhalothrin increased lipid peroxidation in larvae and significantly upregulated AiGSTd expression levels. This study is the first report of molecular characterization of a GST in A. ipsilon, and the present study suggest that AiGSTD might be involved in protecting against the oxidative stress induced by insecticides.