Comparative Toxicity of Chimeric Cry2AX1 Bt Protein Isolated from RecombinantBt and E. coil Hosts against Rice Leaf Folder (Cnaphalocrosis medinalis)

A novel chimeric protein of Bacillus thuringiensis was expressed in two different hosts viz., Bt (4Q7) and E. coli (BL21). The Cry2AX1 protein was expressed in recombinant Bt and E. coli cells harboring cry2AX1 gene driven by cry2Aa and T7 promoter, respectively. There combinant Cry2AX1 protein from Bt and E. coil at 13.33 and 20 ng/μl showed mortality of rice leaf folder (RLF) 86.70 and 56.67 per cent, respectively. These results indicated that the Cry2AX1 protein isolated from Bt was more toxic than that of E. coil, which could be probably due to variation in organization of protein folding between the two hosts. Since the Cry2AX1 protein is effective against RLF even at a very low concentration, further efforts can be made for developing transgenic rice withcry2AX1 gene to import insect resistance.