小菜蛾钙黏蛋白片段对Cry1Ac蛋白的增效作用

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。%It was reported that peptide from toxin-binding region of cadherin receptor in some insects had a syner-gistic effect on Cry1Ac 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 (1 μg/mL)in the presence of PxCAD1(556 μg/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 toxic-ity to P .xylostella larvae with PxCAD2 peptide.Meanwhile,PxCAD1 and PxCAD2 alone were non-toxic to P . xylostella larvae.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.