A method for expressing insecticidal protein structural genes in cotton plant genomes is provided. In the preferred embodiments this invention comprises placing a structural gene for the Bacillus thuringiensis crystal protein under control of a plant or a T-DNA promoter and ahead of a polyadenylation site followed by insertion of said promoter/structural gene combination into a plant genome by utilizing an Agrobacterium tumefaciens Ti plasmid-based transformation system. The modified Ti plasmid is then used to transform recipient plant cells. Also provided are the plants and tissues produced by this method and bacterial strains, plasmids, and vectors useful for execution of this invention.