The overexpression and variant of a P450 gene CYP6G4 associated with propoxur resistance in the housefly, Musca domestica L.

Abstract

BACKGROUND\nThe control of housefly, Musca domestica, heavily relies on the application of insecticides. Propoxur, a carbamate, was widely used for vector control. The housefly populations with high propoxur resistance displayed the point mutations and overexpression of the acetylcholinesterase. However, the roles of cytochrome P450 monoxygenases (P450s), as a kind of the important detoxification enzymes, remain poorly understand in the housefly resistant to propoxur.\n\n\nRESULTS\nP450s were implied to contribute to propoxur resistance based on the synergism of PBO and the increase of P450 enzyme activity in the propoxur resistance near-isogenic line (N-PRS). Five P450 (CYP6G4, CYP6A25, CYP304A1, CYP6D3, and CYP6A1) genes by RNA-seq comparison were significantly up-regulated in the N-PRS strain with >1035-fold resistance to propoxur. A total of thirteen nonsynonymous mutations of three P450 genes (CYP6G4, CYP6D3, and CYP6D8) were found in the N-PRS strain. The amino acid substitutions of CYP6D3 and CYP6D8 were probably not resistance-associated single nucleotide polymorphisms (SNPs) because they were also found in the aabys susceptible strain. However, CYP6G4 variant in the N-PRS strain was not found in the aabys strain. The conjoint analysis of mutations and a series of genetic crosses exhibited that the housefly propoxur resistance was strongly associated with the mutations of CYP6G4 gene.\n\n\nCONCLUSION\nOur results suggested that a combination of upregulated transcript levels and mutations of CYP6G4 contributed to propoxur resistance in the housefly. This article is protected by copyright. All rights reserved.