Overexpression of two α-esterase genes mediates metabolic resistance to malathion in the oriental fruit fly, Bactrocera dorsalis (Hendel).
Esterase has been reported to be involved in malathion resistance in the oriental fruit fly, Bactrocera dorsalis (Hendel). However, the underlying molecular mechanism of the esterase-mediated resistance remains largely unknown in this species. Here, with the use of a strain selected for malathion resistance in the laboratory (MR), we found that two overexpressed α-esterase genes, namely BdCarE4 and BdCarE6, predominant in the adult midgut and fat body, function in conferring malathion resistance in B. dorsalis. Notably, these two genes were found to be mostly close to the esterase E3, which are usually implicated in detoxifying organophosphate insecticides. The transcript levels of BdCarE4 and BdCarE6 were investigated and compared between the MR and a susceptible (MS) strain of B. dorsalis. Both genes were significantly up-regulated in the MR strain, which was consistent with the enhanced esterase activity in the MR strain. However, no changes in either the coding sequence or gene copy number were observed between the two strains. Subsequently, heterologous expression combined with cytotoxicity assay in Sf9 cells demonstrated that BdCarE4 and BdCarE6 can probably detoxify malathion. Furthermore, RNA interference-mediated knockdown of each of these two genes significantly increased malathion susceptibility in the MR strain adults. In conclusion, these results expand our molecular understanding of the important role of α-esterases during the development of resistance to organophosphorous insecticides in B. dorsalis.
Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China.
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LL
Wang
Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China.
Y
Y
Huang
Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China.
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XP
Lu
Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China.
X-Z
XZ
Jiang
Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China.|Department of Crop Protection, Ghent University, Ghent, Belgium.
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G
Smagghe
Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China.
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ZJ
Feng
Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China.
G-R
GR
Yuan
Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China.
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D
Wei
Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China.
J-J
JJ
Wang
D000595:Amino Acid Sequence; D000818:Animals; D004950:Esterases / Q000235:genetics*; D005260:Female; D008658:Inactivation, Metabolic / Q000235:genetics; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D007305:Insecticide Resistance / Q000235:genetics*; D007306:Insecticides / Q000494:pharmacology*; D008294:Malathion / Q000494:pharmacology*; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D034622:RNA Interference; D033621:Tephritidae / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics
D019476:Insect Proteins; D007306:Insecticides; D004950:Esterases; D008294:Malathion
RNA interference; cytotoxicity assay; heterologous expression; metabolic resistance; α-esterase