Full Length Research Paper

CRY 1AB trangenic cowpea obtained by nodal electroporation

Adenubi Adesoye^1,2*, Jesse Machuka²  and  Adeniyi Togun¹

¹Department of Crop Protection and Environmental Biology, University of Ibadan, Nigeria.

²Department of Biochemistry and Biotechnology, Kenyatta University, P.O. Box 43844, Thika Road, Nairobi, Kenya.

*Corresponding author. E-mail: aadesoye@yahoo.com, a.adesoye@mail.ui.edu.ng. Tel: 234-805-1020467.

Former Address: Biotechnology Research Unit, International Institute of Tropical Agriculture, Ibadan, Nigeria.

Accepted 14 August, 2008

Electroporation-mediated genetic transformation was used to introduce Cry 1 Ab insecticidal gene into cowpea. Nodal buds were electroporated in planta with a plasmid carrying the Cry 1Ab and antibiotic resistance npt II genes driven by a 35S CaMV promoter. T₁ seeds derived from electroporated branches were selected in vitro on a medium containing geneticin. PCR and Southern blot analyses confirmed the stable integration of the Cry 1Ab gene into genome of transgenic T₁ cowpea plants. Copy numbers of the gene in cowpea were estimated to be between one to three per genome. However transgene integration occurred at high molecular weights and corresponded to the hybridisation bands obtained for plasmid control. When tested for resistance to Maruca vitrata, T₁ plant progenies reduced larval survival to as low as 11% three days after infestation (DAI). T₂ progenies of Cry 1Ab transgenic lines also positively hybridised with npt II probes when subjected to southern analyses. T₃ progenies significantly reduced larval survival and larval weight and inhibited M. vitrata feeding on cowpea leaves.

Key words: Cowpea transformation, in planta, nodal bud electroporation, Maruca vitrata, genetic engineering, Bacillus thuringiensis.