Cry1Ac毒素对小菜蛾幼虫中肠蛋白酶和羧酸酯酶活性的影响  

Effects of Cry1Ac toxin on proteases and carboxylesterase activities in the larvael midgut of Plutella xylostella

作　　者：赵爱平[1] 展恩玲 孙聪[1] 刘同先[1,2] 李怡萍[1,2] Zhao Aiping Zhan Enling Sun Cong Liu Tongxian Li Yiping(Key Laboratory of Applied Entomology, Key Laboratory of Plant Protection Resources and Pest Management, College of Plant Protection, Northwest A＆F University, Yangling 712100, Shaanxi Province, China Key Laboratory of Integrated Pest Management on Crops in Northwestern Loess Plateau, Ministry of Agriculture, Northwest A＆F University, Yangling 712100, Shaanxi, China)

机构地区：[1]西北农林科技大学,应用昆虫学重点实验室,植保资源与病虫害治理教育部重点实验室,陕西杨凌712100 [2]西北农林科技大学,农业部西北黄土高原作物有害生物综合治理重点实验室,陕西杨凌712100

出　　处：《植物保护学报》2017年第5期713-720,共8页Journal of Plant Protection

基　　金：国家自然科学基金(31071693);陕西省农业科技创新与攻关项目(2016NY-058);中央高校基本科研业务费专项项目(2014YB087)

摘　　要：为了明确Cry1Ac毒素对小菜蛾Plutella xylostella幼虫中肠蛋白酶和羧酸酯酶活性的影响,利用蛋白酶专性底物测定其中肠各蛋白酶活性在不同缓冲液中的最适pH,并用不同浓度Cry1Ac毒素饲喂小菜蛾幼虫后测定该毒素的致死中浓度LC_(50),观察中肠蛋白酶和羧酸酯酶活性的变化,分析Cry1Ac毒素与昆虫中肠酶活性间的关系。结果表明,小菜蛾幼虫中肠总蛋白酶在Tris-HCl、KH_2PO_4/NaOH和Glycine/NaOH三种缓冲液中最适pH均为11.0;强碱性胰蛋白酶的最适pH分别为10.0、10.5和10.5;弱碱性胰蛋白酶的最适pH均为8.5;胰凝乳蛋白酶的最适pH分别为8.5、9.0和9.0。Cry1Ac毒素对小菜蛾的致死中浓度LC_(50)为0.343μg/mL。用不同浓度Cry1Ac毒素饲喂小菜蛾幼虫后,其中肠各蛋白酶活性均随时间的变化而变化。弱碱性胰蛋白酶和胰凝乳蛋白酶的活性明显升高,且随浓度升高呈上升趋势;在取食36~72 h期间低浓度处理组的羧酸酯酶活性与对照组间无显著差异,而高浓度处理组羧酸酯酶活性显著高于对照组。表明Cry1Ac毒素能够显著影响小菜蛾的中肠蛋白酶和羧酸酯酶活性。To clarify the effects of Cry1Ac toxin on midgut protease and detoxification enzyme activities of Plutella xylostella larvae, the midgut fluid proteinase activities were detected to obtain the optimum pH value in several buffer solutions by using the specific substrates. The LC_（50） of Cry1Ac was determined, when P. xylostella larvae were treated with different concentrations of Cry1Ac, and the insect proteases and carboxylesterase activities were studied. Meanwhile, the relationship between Cry1Ac and these enzyme activities were monitored. The optimum pH levels of midgut total proteases of P. xylostella larvae in the three buffers, Tris-HCl, KH_2PO_4/NaOH, and Glycine/NaOH, were 11.0; those of high-alkaline trypsin were 10.0, 10.5 and 10.5, respectively; those of low-alkaline trypsin were 8.5, 8.5 and 8.5; and those of chymotrypsin were 8.5, 9.0 and 9.0, respectively. The LC_（50） of Cry1Ac for P. xylostella was 0.343 μg/mL. After feeding P. xylostella larvae with different concentrations of Cry1Ac toxin, the protease activities exhibited different trends in feeding time： the low-alkaline trypsin and the chymotrypsin activities of P. xylostella were obviously increased and tended to be more active with increasing concentration. The carboxylesterase activities had no significant changes in low concentration toxin treatment groups after 36-72 h. However, the carboxylesterase activities in high concentration toxin treatment groups were greater than that of the control. The study indicated that the Cry1Ac toxin could significantly affect the protease and carboxylesterase activities of P. xylostella.

关 键 词：小菜蛾 蛋白酶 羧酸酯酶 Cry1Ac毒素 酶活性 

分 类 号：S433.4[农业科学—农业昆虫与害虫防治]