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22 November 2019 The Inducible CYP4C71 Can Metabolize Imidacloprid in Laodelphax striatellus (Hemiptera: Delphacidae)
Qianqian Xiao, Lei Deng, Mohammed Esmail Abdalla Elzaki, Lin Zhu, Yanfei Xu, Xiangyu Han, Chunyu Wang, Zhaojun Han, Min Wu
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Abstract

Laodelphax striatellus (Fallén) is an important rice pest species which has developed high resistance to imidacloprid. Previous studies have demonstrated that CYP6AY3v2 and CYP353D1v2 were constitutively overexpressed in a imidacloprid resistant strain and can metabolize imidacloprid to mediated metabolic resistance. Further studies still needed to explore whether there are other L. striatellus P450 enzymes that can also metabolize imidacloprid. In this study, the expression level of L. striatellus CYP4C71 was significantly upregulated both in laboratory strains and field strains of L. striatellus after imidacloprid treatment for 4 h. The capability of CYP4C71 to metabolize imidacloprid was investigated. The full-length CYP4C71 was cloned, and its open reading frame was 1,515 bp with an enzyme estimated to be 505 amino acid residues in size. Furthermore, CYP4C71 was heterologously expressed along with L. striatellus cytochrome P450 reductase (CPR) in insect cells. A carbon monoxide difference spectra analysis confirmed the successful expression of CYP4C71. The recombinant CYP4C71 showed high P450 O-demethylation activity with PNP as a substrate. In vitro metabolism studies showed that recombinant CYP4C71 can metabolize imidacloprid to an easily excreted hydroxy-form. The rate of imidacloprid depletion in response to imidacloprid concentration revealed Michaelis Menten kinetics (R2 fitted curve = 0.99) with a relative low affinity: Kcat = 0.032 ± 0.009 pmol depleted imidacloprid/min/pmol P450 and Km=85.19 ± 2.93 µM. A relative big Km (85.19 ± 2.93 µM) indicated relative low imidacloprid's affinity for the CYP4C71 enzyme. In conclusion, CYP4C71 was another P450 enzyme that can metabolize imidacloprid with a relatively low affinity.

© The Author(s) 2019. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Qianqian Xiao, Lei Deng, Mohammed Esmail Abdalla Elzaki, Lin Zhu, Yanfei Xu, Xiangyu Han, Chunyu Wang, Zhaojun Han, and Min Wu "The Inducible CYP4C71 Can Metabolize Imidacloprid in Laodelphax striatellus (Hemiptera: Delphacidae)," Journal of Economic Entomology 113(1), 399-406, (22 November 2019). https://doi.org/10.1093/jee/toz292
Received: 14 March 2019; Accepted: 7 October 2019; Published: 22 November 2019
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KEYWORDS
cytochrome P450
expression induction test
imidacloprid
insecticide resistance
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