Isolation and Characterization of a Serine Proteinase Inhibitor cDNA from Cabbage and its Antibiosis in Transgenic Tobacco Plants
D.A. Pulliam
Department of Biology, University of North Carolina, Greensboro, NC 27402-6174, USA and Department of Entomology, New York State Agricultural Experiment Station, Cornell University, Geneva, NY, USA and Syngenta Agribusiness Biotechnology Research, Inc., 3054 Cornwallis Rd., Research Triangle Park, NC 27709, USA
D.L. Williams
Department of Biological Sciences, Illinois State University, Normal, Illinois 61790-4120, USA
C.N. Stewart
11327 Reid Place, Grass Valley, CA 95945, USA
*Author to whom correspondence should be addressed.
Abstract
Plant proteinase inhibitors (PIs) are of special interest because of their role in plant defense against herbivorous insects. We isolated a cDNA clone for a serine PI from Brassica oleracea, cabbage (BoPI). A comparison of the putative coding sequence from the cabbage clone with soybean trypsin inhibitor identified conserved amino acids and peptide motifs. Furthermore, it seems to be a member of a 6-8 gene family in cabbage. The serine PI cDNA was subcloned into a plant expression vector under the control of the CaMV 35S promoter, and transgenic Nicotiana tabacum (tobacco) cv Xanthi were produced to test the ability of BoPI to enhance resistance against insects in a heterologous system. These plants were compared with transgenic plants containing different insect resistance transgenes (proteinase inhibitors and a Bacillus thuringiensis cry1Ac). The transgenic plants containing BoPI gene outperformed over other transgenic plants produced with diffierent PI genes, and compared favorably with Bt cry1Ac transgenic plants in a bioassay with Heliothis virescens, tobacco budworm.
Keywords: Brassica, Herbivory, Insect Resistance, Proteinase inhibitor, Transgenic plants