中文摘要：

根据已报道的昆虫毒素结合区钙黏蛋白片段对Cry1Ac蛋白有增效作用,本文以3龄小菜蛾幼虫为研究对象,选取其钙黏蛋白相同功能区的两个片段,将两个片段进行克隆。通过pGEX-6p-1载体,在大肠杆菌中表达了功能区片段PxCAD1及PxCAD2。使用致死中浓度剂量的CrylAc蛋白（1μg/mL）及较高浓度的PxCAD1（556μg/mL）与PxCAD2（551.25μg/mL）对小菜蛾幼虫进行体外复配生测,结果表明,PxCAD1可使小菜蛾幼虫的致死率上升为85.56%,PxCAD2则不能增强CrylAc蛋白的杀虫活性;而PxCAD1与PxCAD2本身对于小菜蛾幼虫并无毒性。研究结果为筛选有效的协同片段提供了理论依据,对于揭示Bt杀虫蛋白的毒理机制和害虫对Bt杀虫蛋白的抗性机制具有重要意义。

英文摘要：

It was reported that peptide from toxin-binding region of cadherin receptor in some insects had a synergistic effect on Cry1 Ac toxin.Two cadherin gene fragments（PxCAD1 and PxCAD2）from Plutella xylostella were cloned.The functional region fragments PxCAD1 and PxCAD2 were expressed in Escherichia coli by using vector pGEX-6p-1.Bioassays with CrylAc（1μg/mL）in the presence of PxCAD1（556μg/mL）polypeptide and PxCAD2（551.25 μg/mL）polypeptide were performed against P.xylostella larvae.The results showed that PxCAD1 caused a mortality of 85.56%to the larvae,while there was no significant enhancement of CrylAc toxicity to P.xylostellalarvae with PxCAD2 peptide.Meanwhile,PxCAD1 and PxCAD2 alone were non-toxic to P.xylostellalarvae.Our results provided theoretical basis for screening effective synergistic fragments,and had great significance in revealing the mechanism of Bt insecticidal protein and insect resistance to Bt.