斜纹夜蛾SlGSTO2对拟除虫菊酯类和有机磷类杀虫剂体外代谢及其抗氧化活性

Metabolic activity of SlGSTO2 in Spodoptera litura to pyrethroids and organophosphates and its antioxidant activity

拟除虫菊酯类和有机磷类杀虫剂常用来防治包括斜纹夜蛾在内的多种鳞翅目害虫,目前斜纹夜蛾已对这两类杀虫剂产生了不同程度的抗性,谷胱甘肽S-转移酶(glutathione Stransferases,GSTs)广泛参与害虫对杀虫剂抗性的形成。前期通过转录组技术筛选到斜纹夜蛾SlGSTO2基因在拟除虫菊酯高抗种群中显著上调表达,为进一步探究该基因的功能,将其在大肠杆菌中异源表达,并测定重组蛋白对拟除虫菊酯类和有机磷类杀虫剂的代谢活性,同时采用抑菌圈试验测定了其抗氧化活性。结果表明:重组蛋白SlGSTO2仅对三氟氯氰菊酯有微弱的体外代谢活性,而对氰戊菊酯、高效氯氰菊酯、辛硫磷和毒死蜱均无代谢活性;抑菌圈试验结果表明,表达pET-26b(+)/SlGSTO2的大肠杆菌可以显著降低不同浓度过氧化氢异丙苯的抑菌圈直径,说明SlGSTO2具有抗氧化活性。研究结果丰富了对斜纹夜蛾GSTs Omega家族基因的功能认知。

Pyrethroids and organophosphates are commonly used insecticides for the control of lepidoptera pests,including Spodoptera litura,which has developed different level of resistance to these insecticides.Glutathione S-transferases(GSTs)was reported to be widely involved in the resistance to insecticides.Previous study showed that SlGSTO2 was significantly overexpressed in pyrethroidresistant populations when compared with pyrethroid-susceptible population.To further explore its function,SlGSTO2 was heterologously expressed in E.coli and its metabolic activity to pyrethroids and organophosphates were determined.The antioxidant activity of SlGSTO2 was also determined by disc diffusion assay.Results showed that the recombinant protein of SlGSTO2 had slight metabolic activity to cyhalothrin only in vitro,whereas no metabolic activity to fenvalerate,beta-cypermethrin,chlorpyrifos or phoxim.Compared with LB plate transformed with pET-26b(+),the halo diameter of discs soaked with different concentration of cumene hydroperoxide in the plate transformed with pET-26b(+)/SlGSTO2 decreased significantly,indicating obvious antioxidant activity of SlGSTO2.Findings in this study enriched the function of GSTs genes in Omega class in S.litura.