大豆胰蛋白酶抑制剂和防御信号物质对斜纹夜蛾幼虫保护酶的影响

以广食性害虫斜纹夜蛾为研究对象,连续6代自二龄或三龄开始用含有大豆胰蛋白酶抑制剂(soybean trypsin inhibitor,SBTI)的人工饲料喂养幼虫,饲养至五龄时测定SBTI对幼虫保护酶的影响。结果表明,SBTI抑制斜纹夜蛾幼虫SOD、CAT活性,随着饲养代数的增加,SBTI的抑制效果降低;SBTI可显著升高斜纹夜蛾幼虫POD活性。预先接触外源植物防御信号物质茉莉酸甲酯和水杨酸甲酯48h均可显著影响斜纹夜蛾幼虫体内保护酶SOD、POD、CAT活性,且可显著减缓SBTI对斜纹夜蛾幼虫SOD、POD、CAT活性的作用效果。表明,斜纹夜蛾取食SBTI后能够调节自身的保护酶系统,逐步适应蛋白酶抑制剂的毒害,而预先接触植物防御信号物质可增强其对植物防御蛋白的适应能力。

Effects of soybean trypsin inhibitor and defense signaling compounds on the protective enzymes in Spodoptera litura larvae

In this study, the second or third instars of euryphagous insect Spodoptera litura larvae were continuously fed with the diets containing soybean trypsin inhibitor (SBTI) for six generations, and the protective enzyme activities in the midgut and fatbody of the fifth instars of S. litura larvae were evaluated. SBTI inhibited the SOD and CAT activities, but the inhibition effect decreased with the increase of successive culture generation. On the other hand, SBTI promoted the POD activity significantly. Pre-exposure to methyl jasmonate and salicylate for 48 h had significant effects on the SOD, POD and CAT activities, and decreased the effects of SBTI on these protective enzymes activities significantly. These results suggested that S. litura could regulate its protective enzyme system and gradually adapt to protease inhibitors, while pre-exposure to volatile defense signaling compounds could enhance the adaptation of S. litura to plant defense proteins.