Identification and characterization of glutathione S-transferases and their potential roles in detoxification of abamectin in the rice stem borer, Chilo suppressalis

The glutathione S-transferases (GSTs) are a kind of metabolic enzymes and participate in the detoxification metabolism of xenobiotics in various organisms. In insects, GSTs play important roles in the development of insecticide resistance and antioxidant protection. The rice stem borer Chilo suppressalis is one of the most damaging pests in rice and has developed high levels of resistance to abamectin in many areas of China, whereas the potential resistance mechanisms of C suppressalis to abamectin are still unclear. In the present study, a total of 23 CsGSTs genes were identified from the C. suppressalis transcriptome and genome, including 21 cytosolic and two microsomal CsGSTs. The cytosolic CsGSTs were further classified into seven categories based on phylogenetic analysis, and their sequence characteristics and genome structures were also analyzed. Synergism study revealed that the susceptibility of C. suppressalis to abamectin was increased significantly when the CsGSTs were inhibited by diethyl maleate (DEM). Sixteen CsGSTs genes were up-regulated in C. suppressalis larvae after treatment with abamectin, among which four CsGSTs genes including CsGSTe2, CsGSTe4, CsGSTo4 and CsGSTu1 were significantly induced in the midgut and fat body tissues. These results indicated that CsGSTs were associated with the detoxification of C. suppressalis to abamectin, and CsGSTe2, CsGSTe4, CsGSTo4 and CsGSTu1 might play important roles in the insecticide detoxification or antioxidant protection in C. suppressalis. Our present study provides valuable information on C. suppressalis GSTs, and are helpful in understanding the contributions of GSTs in abamectin detoxification in C. suppressalis and other insects.