The expression level of cytochrome P450 genes in insects can be induced by plant allelochemicals,which is important for insects to adapt to host plants.Cytochrome P450CYP6B 7has been reported to be involved in pyethroid insecticide resistance in Heli- coverpa armigera,and its transcription level was induced by some inducers.Currently,the regulatory mechanism of the induced expression of CYP6B7remains unknown,although it is very important for understanding the detoxification mechanism to allelochemicals in host plants.The objective of the present study was to investigate the eis-acting ele- ment in the promoter of CYP6B7 mediating the inducible up-regulation of CYP6B7in H.armigera by 2-tridecanone.The promoter region of CYP6B7was cloned by genome walking technique and analyzed by transient transfeetion assay.Progressive 5'deletion of the promoter region of CYP6B7revealed that the relative luciferase activity of construct -320/+232could be significantly induced by 2-trideeanone.Further stepwise deletion between -320 and -238 bp found that construct -292/+232 could also be significantly induced by 2-tridecanone,but the adjacent construct -256/+232could not,suggesting the essential role of the sequence between -292 and --257 bp for 2-tridecanone induction. Nucleotide mutations between -292 and -281 bp had no influence on the induction ef- fect by 2-tridecanone,but nucleotide mutations between -280 and -257 bp significantly decreased the induction effect.These results demonstrated that the cis-acting element for 2-trideeanone induction was between -280 and -257 bp in the promoter of CYP6B7.
Li XuDong-Zhi LiYuan-Yuan LuoJian-Ying QinLi-Hong Qiu
