Abstract
Cytochrome P450 monooxygenases (CYPs or P450s) play paramount roles in detoxification of insecticides in a number of insect pests. However, little is known about the roles of P450s and their responses to insecticide exposure in the codling moth Cydia pomonella (L.), an economically important fruit pest. Here we report the characterization and expression analysis of the first P450 gene, designated as CYP9A61, from this pest. The full-length cDNA sequence of CYP9A61 is 2071 bp long and its open reading frame (ORF) encodes 538 amino acids. Sequence analysis shows that CYP9A61 shares 51%–60% identity with other known CYP9s and contains the highly conserved substrate recognition site SRS1, SRS4 and SRS5. Quantitative real-time PCR showed that CYP9A61 were 67-fold higher in the fifth instar larvae than in the first instar, and more abundant in the silk gland and fat body than other tissues. Exposure of the 3rd instar larvae to 12.5 mg L−1 of chlorpyrifos-ethyl for 60 h and 0.19 mg L−1 of lambda-cyhalothrin for 36 h resulted in 2.20-and 3.47-fold induction of CYP9A61, respectively. Exposure of the 3rd instar larvae to these two insecticides also significantly enhanced the total P450 activity. The results suggested that CYP9A61 is an insecticide-detoxifying P450.
Highlights
The codling moth Cydia pomonella (L.) (Lepidoptera: Tortricidae) is one of the most serious pests of pome fruits and walnuts in many countries where these crops are cultivated [1,2,3,4,5,6]
The spatiotemporal and insecticide-induced expression profiles of CYP9A61 revealed by real-time quantitative PCR (RT-Quantitative PCR (qPCR)) suggest that it is a xenobiotic-metabolizing P450 gene
Third instar larvae were treated with chlorpyrifos-ethyl and lambda-cyhalothrin, and their mRNA expression levels were detected by RT-qPCR
Summary
The codling moth Cydia pomonella (L.) (Lepidoptera: Tortricidae) is one of the most serious pests of pome fruits and walnuts in many countries where these crops are cultivated [1,2,3,4,5,6]. A major problem associated with chemical control of the codling moth is its development of resistance to insecticide groups organophosphates (OPs) [7,8,9,10] and synthetic pyrethroids (SPs) [11,12,13] in many countries. Cytochrome P450 monooxygenases (CYPs or P450s) are a superfamily of enzymes responsible for detoxification of natural and synthetic xenobiotics including insecticides and plant toxins [14,15,16,17,18,19]. In C. pomonella, extensive studies have suggested that P450s may play a key role in detoxification of OP and SP due to the observed significantly higher total P450 enzyme activity in the resistant. The spatiotemporal and insecticide-induced expression profiles of CYP9A61 revealed by real-time quantitative PCR (RT-qPCR) suggest that it is a xenobiotic-metabolizing P450 gene
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