大豆胰蛋白酶抑制剂和防御信号物质对斜纹夜蛾解毒酶的影响

在昆虫与植物漫长的相互作用中,植物合成多种抗虫物质并采用防御信号转导系统抵御昆虫,昆虫也具有多种解毒酶系统保护其免受植物毒素的毒害.本文研究了人工添加大豆胰蛋白酶抑制剂和植物防御信号物质对斜纹夜蛾幼虫羧酸酯酶和谷胱甘肽-S-转移酶活性的影响.结果表明:持续6代自幼虫2龄或3龄开始喂养含有大豆胰蛋白酶抑制剂的人工饲料,其5龄幼虫中肠和脂肪体内羧酸酯酶、谷胱甘肽-S-转移酶活性显著升高,2、3龄处理的继代幼虫中肠和脂肪体内羧酸酯酶活性均在第二代达到最大值,分别为对照的2.06、2.40倍和1.96、2.70倍；其谷胱甘肽-S-转移酶活性则分别于第4、2代达到最大值,分别为对照的7.03、11.58倍和5.71、3.60倍,并呈现先升高再降低的趋势.预先接触外源信号物质茉莉酸甲酯、水杨酸甲酯48 h和添加大豆胰蛋白酶抑制剂均可使斜纹夜蛾幼虫中肠、脂肪体内羧酸酯酶和谷胱甘肽-S-转移酶的活性显著升高,且预先接触茉莉酸甲酯和水杨酸甲酯48 h可减缓大豆胰蛋白酶抑制剂对幼虫中肠和脂肪体内羧酸酯酶、谷胱甘肽-S-转移酶活性的作用效果.

Effects of soybean trypsinase inhibitor and defense signaling compounds on detoxification enzymes in Spodoptera litura(F.) larvae

In a long history of interactions between insects and plants,plants have developed various anti-insect compounds and defense signaling transduction pathways to defend against herbivorous insects,while insects have responded with sophisticated detoxification enzyme systems to protect against the toxicity of anti-insect compounds.In this study,the 2nd or 3rd instar of Spodoptera litura larvae were successively fed with the diets containing 0.5% soybean trypsinase inhibitor(SBTI) for six generations to evaluate the effects of SBTI and defense signaling compounds on the activities of detoxification enzymes carboxylesterase(CarE) and glutathione-S-transferase(GST) in the midgut and fatbody of the larvae.After fed with the diets,the CarE and GST activities in the 5th instar larvae increased significantly.The CarE activity in the midgut and fatbody of the second generation larvae was the highest,being 2.06 and 2.40 times,and 1.96 and 2.70 times of that of the control,and the GST activity in the midgut and fatbody of the fourth and second generations was the highest,being 7.03 and 11.58 times,and 5.71 and 3.60 times of that of the control,respectively.These induced enzyme activities decreased gradually when the larvae continuously grew with the SBTI-containing diets.In addition,when the S.litura larvae were pre-exposed to methyl jasmonate(MeJA) or methyl salicylate(MeSA) for 48 h or fed with the diets containing 0.5% SBTI,the activities of CarE and GST in the midgut and fatbody increased significantly,and,when the 2nd instar larvae were pre-exposed to MeJA and MeSA for 48 h,the effects of SBTI on the GST activity in larval midgut and fatbody were reduced.