Development of insect-resistant transgenic plants using plant genes: Expression of cowpea trypsin inhibitor in transgenic tobacco plants

Development of transgenic plants, engineered for insect resistance, has added a new dimension to crop improvement. The cowpea trypsin inhibitor (CpTI) gene offers resistance against a wide range of insects, and has been used for developing insect-resistant plants. In the present study, the CpTI gene, amplified by PCR, was cloned in a plant expression vector under the control of the CaMV 35S promoter and the NOS terminator, and introduced into model plant tobacco by Agrobacterium-mediated transformation. The presence and expression of the CpTI gene in primary transformants R-0 and R-1 progeny was confirmed by PCR and immunobiochemical analyses. The efficacy of the expressed CpTI protein against Spodoptera litura was tested by feeding trial larvae under laboratory conditions. Reduction to the extent of 50% was observed in the biomass of S. litura larvae fed on transgenic leaves, expressing 3-5 mu g CpTI/g fresh tissue.