Abstract:

【Objective】 This study was conducted to build a recombinant strain with highly insecticidal activity and a wide host range by using the cry1Ac gene and p74 gene. 【Method】 Firstly, the p74 gene was amplified from the genosome of Autographa californica multicapsid nucleopolyhedrovirus, the cry1Ac gene and the terminator gene of cry1Ac, named cry1Act, were amplified from the plasmid of Bt 4.0718 strain. Three T vectors, named pTp74, pT1Ac and pT1Act which held the aimed gene p74, cry1Ac and cry1Act, respectively, and two middle vectors, named pTp74Act and pT1Acp74 which held the aimed fusion gene p74-cry1Act and cry1Ac-p74, respectively, were built by using pMD18-T. Then pT1Acp74 and the shuttle plasmid were digested and linked, and an expressing-vector pH1Acp74 was built. Finally, pH1Acp74 was transformed into the acrystalliferous strain XBU001 and the aimed recombinant strain XBU-H1Acp74 were obtained. 【Result】 The expression of Bt transformant XBU-H1Acp74 was analyzed by SDS-PAGE, which showed XBU-H1Acp74 could produce 130 kD Cry1Ac protein and 50 kD P74 protein. The insecticidal activity of transformant against Helicoverpa armigera Hubner was evaluated compared with the contrast strains HTX-42 (only cry1Ac gene was transformed into XBU001) after autolysis. The LC50 of HTX-42 was higher than the XBU-H1Acp74’s, which implied that P74 could increase the efficacy and range of Bt Cry toxins in insect control. 【Conclusion】 This work constructed the fusion gene of cry1Ac and p74 successfully, which made a good ground for constructing the fusion genes of Bt cry gene and other foreign genes.

Key words: Bacillus thuringiensis, Autographa californica multicapsid nucleopolyhedrovirus, cry1Ac gene, p74 gene, fusing gene