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The wild-type Crylle gene from Bacillus thuringiensis was modified for its efficient expression in transgenic plants. Modified Cry1 Ie gene (designated as Cry1 Iem) was cloned into prokaryotic expression vector pET28b and its expression in E. coli was confirmed by SDS-PAGE analysis. Bioassays using crude expression products in E. coli revealed that Cry1 Iem protein had a similar toxicity to co borer as wild-type Cry1 Ie. Cry1 Iem gene was then inserted downstream of the maize ubiquitin-1 promoter in plant expression vector p3301. Transgenic tobacco plants carrying Cry1 Iem showed insecticidal activity against com borer.