Wang L-L, Huang Y, Lu X-P, Jiang X-Z, Smagghe G, Feng Z-J, Yuan G-R, Wei D, Wang J-J
Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China.
Department of Crop Protection, Ghent University, Ghent, Belgium.
Insect Mol Biol. 2015 Aug;24(4):467-79. doi: 10.1111/imb.12173. Epub 2015 May 4.
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.
据报道，酯酶与东方果实蝇（橘小实蝇，Bactrocera dorsalis (Hendel)）对马拉硫磷的抗性有关。然而，在该物种中，酯酶介导抗性的潜在分子机制仍 largely 未知。在此，我们使用在实验室中筛选出的对马拉硫磷具有抗性的品系（MR），发现两个过表达的α-酯酶基因，即BdCarE4和BdCarE6，在成虫中肠和脂肪体中占主导地位，在赋予橘小实蝇对马拉硫磷的抗性中起作用。值得注意的是，发现这两个基因大多与酯酶E3接近，酯酶E3通常参与有机磷杀虫剂的解毒。研究并比较了橘小实蝇MR品系和敏感（MS）品系之间BdCarE4和BdCarE6的转录水平。这两个基因在MR品系中均显著上调，这与MR品系中酯酶活性增强一致。然而，在两个品系之间未观察到编码序列或基因拷贝数的变化。随后，在Sf9细胞中进行的异源表达结合细胞毒性测定表明，BdCarE4和BdCarE6可能对马拉硫磷进行解毒。此外，RNA干扰介导的对这两个基因中每个基因的敲低显著增加了MR品系成虫对马拉硫磷的敏感性。总之，这些结果扩展了我们对α-酯酶在橘小实蝇对有机磷杀虫剂抗性发展过程中重要作用的分子理解。
