title: The roles of CYP6AY1 and CYP6ER1 in imidacloprid resistance in the brown planthopper: Expression levels and detoxification efficiency.
abstract: Two P450 monooxygenase genes, CYP6AY1 and CYP6ER1, were reported to contribute importantly to imidacloprid resistance in the brown planthopper, Nilaparvata lugens. Although recombinant CYP6AY1 could metabolize imidacloprid efficiently, the expression levels of CYP6ER1 gene were higher in most resistant populations. In the present study, three field populations were collected from different countries, and the bioassay, RNAi and imidacloprid metabolism were performed to evaluate the importance of two P450s in imidacloprid resistance. All three populations, DOT (Dongtai) from China, CNA (Chainat) from Thailand and HCM (Ho Chi Minh) from Vietnam, showed high resistance to imidacloprid (57.0-, 102.9- and 89.0-fold). CYP6AY1 and CYP6ER1 were both over expressed in three populations, with highest ratio of 13.2-fold for CYP6ER1 in HCM population. Synergism test and RNAi analysis confirmed the roles of both P450 genes in imidacloprid resistance. However, CYP6AY1 was indicated more important in CNA population, and CYP6AY1 and CYP6ER1 were equal in HCM population, although the expression level of CYP6ER1 (13.2-fold) was much higher than that of CYP6AY1 (4.11-fold) in HCM population. Although the recombinant proteins of both P450 genes could metabolize imidacloprid efficiently, the catalytic activity of CYP6AY1 (Kcat=3.627 pmol/min/pmol P450) was significantly higher than that of CYP6ER1 (Kcat=2.785 pmol/min/pmol P450). It was supposed that both P450 proteins were important for imidacloprid resistance, in which CYP6AY1 metabolized imidacloprid more efficiently and CYP6ER1 gene could be regulated by imidacloprid to a higher level.
authors.affiliation: Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, St. Zhongling 50, Nanjing 210014, China; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Weigang 1, Nanjing 210095, China.
authors.forename: Haibo
authors.initials: H
authors.lastname: Bao
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Weigang 1, Nanjing 210095, China.
authors.forename: Hongli
authors.initials: H
authors.lastname: Gao
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Weigang 1, Nanjing 210095, China.
authors.forename: Yixi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Weigang 1, Nanjing 210095, China.
authors.forename: Dongzhe
authors.initials: D
authors.lastname: Fan
authors.affiliation: Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, St. Zhongling 50, Nanjing 210014, China.
authors.forename: Jichao
authors.initials: J
authors.lastname: Fang
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Weigang 1, Nanjing 210095, China. Electronic address: liuzewen@njau.edu.cn.
authors.forename: Zewen
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D006430:Hemiptera / Q000187:drug effects* / Q000201:enzymology; D007093:Imidazoles / Q000633:toxicity*; D007306:Insecticides / Q000633:toxicity*; D007527:Isoenzymes / Q000378:metabolism*; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000633:toxicity*
chemical_list: D007093:Imidazoles; D007306:Insecticides; D007527:Isoenzymes; D000073943:Neonicotinoids; D009574:Nitro Compounds; C082359:imidacloprid; D003577:Cytochrome P-450 Enzyme System
keywords: CYP6AY1 and CYP6ER1; Nilaparvata lugens; P450s; Resistance contribution