Li-Wei Meng1,2, Meng-Lan Peng1, Meng-Ling Chen1, Guo-Rui Yuan1,2, Li-Sha Zheng1,2, Wen-Jie Bai1, Guy Smagghe1,2,3, Jin-Jun Wang1,2. 1. Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China. 2. International Joint Laboratory of China-Belgium on Sustainable Crop Pest Control, State Cultivation Base of Crop Stress Biology for Southern Mountainous Land, Academy of Agricultural Sciences, Southwest University, Chongqing, China. 3. Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
Abstract
BACKGROUND: The oriental fruit fly, Bactrocera dorsalis (Hendel), is a widespread agricultural pest that has evolved resistance to many commonly used insecticides including malathion. Glutathione S-transferases (GSTs) are multifunctional enzymes that metabolize insecticides directly or indirectly. The specific mechanism used by GSTs to confer malathion resistance in B. dorsalis is unclear. RESULTS: BdGSTd9 was identified from B. dorsalis and was expressed at twice the level in a malathion-resistant strain (MR) than in a susceptible strain (MS). By using RNAi of BdGSTd9, the toxicity of malathion against MR was increased. Protein modelling and docking of BdGSTd9 with malathion and malaoxon indicated key amino acid residues for direct binding in the active site. In vitro assays with engineered Sf9 cells overexpressing BdGSTd9 demonstrated lower cytotoxicity of malathion. High performance liquid chromatography (HPLC) analysis indicated that malathion could be broken down significantly by BdGSTd9, and it also could deplete the malathion metabolite malaoxon, which possesses a higher toxicity to B. dorsalis. Taken together, the BdGSTd9 of B. dorsalis could not only deplete malathion, but also react with malaoxon and therefore enhance malathion resistance. CONCLUSION: BdGSTd9 is a component of malathion resistance in B. dorsalis. It acts by depleting both malathion and malaoxon.
BACKGROUND: The oriental fruit fly, Bactrocera dorsalis (Hendel), is a widespread agricultural pest that has evolved resistance to many commonly used insecticides including malathion. Glutathione S-transferases (GSTs) are multifunctional enzymes that metabolize insecticides directly or indirectly. The specific mechanism used by GSTs to confer malathion resistance in B. dorsalis is unclear. RESULTS: BdGSTd9 was identified from B. dorsalis and was expressed at twice the level in a malathion-resistant strain (MR) than in a susceptible strain (MS). By using RNAi of BdGSTd9, the toxicity of malathion against MR was increased. Protein modelling and docking of BdGSTd9 with malathion and malaoxon indicated key amino acid residues for direct binding in the active site. In vitro assays with engineered Sf9 cells overexpressing BdGSTd9 demonstrated lower cytotoxicity of malathion. High performance liquid chromatography (HPLC) analysis indicated that malathion could be broken down significantly by BdGSTd9, and it also could deplete the malathion metabolite malaoxon, which possesses a higher toxicity to B. dorsalis. Taken together, the BdGSTd9 of B. dorsalis could not only deplete malathion, but also react with malaoxon and therefore enhance malathion resistance. CONCLUSION: BdGSTd9 is a component of malathion resistance in B. dorsalis. It acts by depleting both malathion and malaoxon.
Authors: Nadja C Wipf; Wandrille Duchemin; France-Paraudie A Kouadio; Behi K Fodjo; Christabelle G Sadia; Chouaïbou S Mouhamadou; Laura Vavassori; Pascal Mäser; Konstantinos Mavridis; John Vontas; Pie Müller Journal: PLoS Genet Date: 2022-02-10 Impact factor: 5.917