Involvement of Glutamate Cysteine Ligase Genes in Tolerance to Emamectin Benzoate in Spodoptera frugiperda and Their Putative Regulatory Mechanisms.

As the rate-limiting enzyme in Glutathione (GSH) biosynthesis, the mammalian glutamate cysteine ligase (Gcl) catalytic (Gclc) and modifier (Gclm) subunits are regulated at multiple levels, whereas the function and regulatory mechanism of insect Gcl remain to be explored. In this study, we identified and characterized and in . and were highly expressed in the hindgut and relatively less expressed in other tissues. The exposure of the third instar larvae to LC of emamectin benzoate (EMB) significantly reduced the GSH content with a concomitant upregulation of and Further pretreatment with L-BSO, the Gcl inhibitor, increased the susceptibility of to EMB. Consistently, overexpression of and increased the Sf9 cell viability under EMB treatment. Finally, both RNAi and the dual-luciferase reporter assay in Sf9 cells revealed that is regulated by transcription factor CncC. These data provide insights into the function and regulatory mechanism of insect Gcl, and they imply that disruption of the redox homeostasis might be a practical strategy to enhance the insecticidal activity of EMB and other insecticides.