Abstract:Soybean Kunitz trypsin inhibitor belongs to protease inhibitor family with insecticidal properties. The soybean Kunitz trypsin inhibitor gene was obtained from the template cDNA which was synthesized from the total RNA of the isolated soybean ( Glycine max L. ) immature cotyledons by PCR, and cloned into Sma I site of pBluescript KS( + ). DNA sequence analysis indicated that the cloned 663 bp DNA fragment carried the entire coding sequence, which encoded a precursor composed of 217 amino acids, including a signal peptide composed of 25 amino acids at the N terminus, the mature protein composed of 181 amino acids and an extra 11 amino acids at the C tenninus. A series of plant expression vectors have been constructed for tobacco (Nicotiana tabacum L. ), rice ( Oryza sativa L. ) and cotton ( Gossypium hirsutum L. ) transformation. The transgenic tobacco was confirmed by PCR and Southern blotting. Data from bioassays of insects showed that the transgenic tobacco displayed notably resistance to the larvae of Heliothis armigera Hubner compared with wild tobacco.