Down-regulation of lysosomal protein ABCB6 increases gossypol susceptibility in Helicoverpa armigera.

Cotton bollworm (Helicoverpa armigera) is the major insect herbivore of cotton plants. As its larvae feed and grow on cotton, H. armigera can likely tolerate gossypol, the main defense metabolite produced by cotton plants, through detoxification and sequestration mechanisms. Recent reports have shown that various P450 monooxygenases and UDP-glycosyltransferases in H. armigera are involved in gossypol detoxification, while the roles of ABC transporters, another gene family widely associated with metabolite detoxification, remain to be elucidated. Here, we show that ingestion of gossypol-infused artificial diet and cotton leaves significantly induced the expression of HaABCB6 in H. armigera larvae. Knockdown and knockout of HaABCB6 increased sensitivity of H. armigera larvae to gossypol. Moreover, HaABCB6-GFP fusion protein was localized on lysosomes in Hi5 cells and its overexpression significantly enhanced gossypol tolerance in vitro. These experimental results strongly support that HaABCB6 plays an important role in gossypol detoxification by H. armigera.