Transgenic sweet potato plants carrying the delta-endotoxin gene from Bacillus thuringiensis var. tenebrionis.

Abstract

Some clones of sweet potato (Ipomoea batatas L.), transgenic plants of the cultivar ‘Jewel’, carrying the cryIIIA gene from Bacillus thuringiensis subsp. tenebrionis (B.t.t), were obtained. Molecular tests and biological activity experiments against sweet potato weevil (Cylas formicarius), were performed. The cryIIIA delta-endotoxin gene was cloned under the regulation of the 35S CaMV promoter and the TMV Omega fragment. The neomycin phosphotransferase (nptII) gene for kanamycin resistance was used as selection marker. An efficient protocol for in vitro plant regeneration, which combines naphtalenacetic acid (NAA) and 6-benzilaminopurin (BAP), was established. An Agrobacterium tumefaciens-mediated transformation protocol for sweet potato was implemented. An increase of the transformation frequency of sweet potato, compared to that previously reported, was obtained. Biological activity experiments to evaluate the insecticidal capacity of transgenic plants were performed against sweet potato weevil under both controlled, and field conditions. Plants from the two best resulting clones were tested by molecular methods such as RNA. dot blot and Western blot.