P450基因组成型过量表达与棉铃虫对拟除虫菊酯的抗性

Our previous studies showed that enhanced cytochrome P450-mediated detoxification is a major mechanism responsible for pyrethroid resistance in a laboratory-selected strain (YGF) of Helicoverpa armigera. Two new cytochrome P450 genes CYP9A12, CYP9A14 (encoding 531 and 530 amino acid residues, respectively) were isolated from the fatbody of the YGF strain of H. armigera. The mRNA expression levels of above two CYP9 P450 genes, together with CYP6B7 and CYP4G8 (previously reported to be overexpressed in pyrethroid-resistant strains), were assessed by real-time quantitative RT-PCR in the final instar larvae of a field-derived YG strain (with 7-fold resistance to the pyrethroid fenvalerate) and the YGF strain (selected from the YG strain with fenvalerate in the laboratory, with 1690-fold resistance to fenvalerate). The mRNA expression levels of CYP9A12, CYP9A14 and CYP6B7 in the fatbody of the YGF strain increased to 433-, 59- and 9.3-fold respectively compared with the YG strain, whereas no overexpression was revealed for CYP4G8. CYP9A12 and CYP9A14 had 19- and 4.3-fold overexpression in the midgut of the YGF strain compared with the YG strain respectively, but CYP6B7 and CYP4G8 were not overexpressed. The present study provided evidence that constitutive overexpression of multiple cytochrome P450 genes (CYP9A12, CYP9A14 and CYP6B7) is associated with pyrethroid resistance in H. armigera.