Transcription factor CncC potentially regulates cytochrome P450 CYP321A1-mediated flavone tolerance in Helicoverpa armigera.

Insect P450s play crucial roles in metabolizing insecticides and toxic plant allelochemicals. In this study, our results demonstrate that Helicoverpa armigera can adapt to a lower concentration of flavone (a flavonoid phytochemical), and P450 activities and CYP321A1 transcript levels significantly increase after exposure to flavone. RNAi-mediated knockdown of CYP321A1 significantly reduced the tolerance of H. armigera larvae to flavone. In addition, the regulatory mechanisms driving CYP321A1 induction following exposure to flavone were investigated. Flavone exposure significantly increased H2O2 generation in the larval midgut. The mRNA levels of HaCncC and HaMaf-s significantly increased in the midgut of H. armigera after exposure to flavone. Knockdown of HaCncC significantly inhibited expression of flavone-induced CYP321A1 and resulted in a decrease in flavone induction of CYP321A1. HaCncC knockdown significantly reduced the tolerance of H. armigera larvae to flavone. Taken together, these results indicate that HaCncC regulates expression of the CYP321A1 gene responsible for flavone tolerance in H. armigera.