title: The epsilon glutathione S-transferases contribute to the malathion resistance in the oriental fruit fly, Bactrocera dorsalis (Hendel).
abstract: Epsilon glutathione S-transferases (eGSTs) play important roles in xenobiotics detoxification and insecticides resistance in insects. However, the molecular mechanisms of eGSTs-mediated insecticide resistance remain largely unknown in the Bactrocera dorsalis (Hendel), one of the most notorious pests in the world. Here, we investigated the roles of eight GST genes which belonged to epsilon class (BdGSTe1, BdGSTe2, BdGSTe3, BdGSTe4, BdGSTe5, BdGSTe6, BdGSTe7 and BdGSTe9) in conferring malathion resistance in B. dorsalis. Adult developmental stage-, sex- and tissue-specific expression patterns of the eight eGST genes were analyzed via quantitative reverse transcription PCR. The results showed that BdGSTe2, BdGSTe3, BdGSTe4 and BdGSTe9 were abundant in the midgut, fat body and Malpighian tubules. Notably, BdGSTe2, BdGSTe4 and BdGSTe9 were significantly overexpressed in a malathion-resistant (MR) strain of B. dorsalis compared to the malathion-susceptible (MS) strain. Functional expression and cytotoxicity assays showed significantly higher malathion detoxification capabilities in BdGSTe2-, BdGSTe3-, BdGSTe4- and BdGSTe9-expressing Sf9 cells compared to the parental and green fluorescent protein (GFP)-expressing Sf9 cells. Moreover, malathion susceptibility in MS adults was increased 30%, 14%, and 33% when BdGSTe2, BdGSTe3 and BdGSTe4 mRNA levels were repressed by RNA interference (RNAi)-mediated knockdown, respectively. Taken together, overexpression of the isoforms of eGSTs, including BdGSTe2, BdGSTe4, and particularly, BdGSTe9 plays an important role in the malathion resistant development in B. dorsalis.
authors.affiliation: Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400716, PR China.
authors.forename: Xue-Ping
authors.initials: XP
authors.lastname: Lu
authors.affiliation: Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400716, PR China.
authors.forename: Luo-Luo
authors.initials: LL
authors.lastname: Wang
authors.affiliation: Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400716, PR China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400716, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Dou
authors.affiliation: Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400716, PR China.
authors.forename: Chang-Tong
authors.initials: CT
authors.lastname: Chen
authors.affiliation: Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400716, PR China.
authors.forename: Dong
authors.initials: D
authors.lastname: Wei
authors.affiliation: Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400716, PR China. Electronic address: jjwang7008@yahoo.com.
authors.forename: Jin-Jun
authors.initials: JJ
authors.lastname: Wang
mesh_terms: D000818:Animals; D002460:Cell Line; D015971:Gene Expression Regulation, Enzymologic; D020868:Gene Silencing; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism*; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D007527:Isoenzymes; D008294:Malathion / Q000494:pharmacology*; D033621:Tephritidae / Q000187:drug effects*
chemical_list: D007306:Insecticides; D007527:Isoenzymes; D005982:Glutathione Transferase; D008294:Malathion
keywords: Glutathione S-transferases; Heterologous expression; MTT assay; Malathion resistance; Oriental fruit fly; RNAi