Promoters of the two novel cytochrome P450 genes, CYP6DD1 and CYP307A2 from Sitobion miscanthi and their mediation under insecticide exposure

Abstract

The detoxification mediated by cytochrome P450 is always involved in insecticide resistance. Our previous studies have demonstrated that multiple P450 genes were overexpressed in the imidacloprid-resistant strain (SA-R) in Sitobion miscanthi. However, the characterization and transcriptional regulation of these related P450 genes were unknown. To understand the regulation mechanisms, the promoter of the two P450 genes, CYP6DD1 and CYP307A2, were obtained and analyzed under the induction of these two neonicotinoid insecticides, indicating that the transcript levels of CYP6DD1 and CYP307A2 were significantly induced by both imidacloprid and thiamethoxam. Furthermore, the overexpression in the imidacloprid-resistant strain (SA-R), and the increased sensitivity of S. miscanthi to these two neonicotinoid insecticides after knockdown of CYP6DD1 and CYP307A2 were all observed, suggesting that CYP6DD1 and CYP307A2 could be involved in the resistance of S. miscanthi to some neonicotinoids. Subsequently, we examined the regulatory mechanism of CYP6DD1 and CYP307A2 based on the transcriptional level. The promoter regions from −610 to +182 bp, and from −292 to +236 bp were critical for transcription activities of CYP6DD1 and CYP307A2, respectively. The cis-elements between −368 and −244 bp of CYP6DD1, and between −128 and + 144 bp of CYP307A2, were identified as insecticide responsive regions. The binding site of a potential nuclear factor erythroid 2-related factor 2 (Nrf2) was found with a conserved sequence motif 5′-CA/TCAGCAT/C-3′. It is of great significance to understand this regulatory mechanism of P450 expression in the resistance of Sitobion miscanthi to neonicotinoids.