Insect resistance of transgenic plants that express modified Bacillus thuringiensis cryIA(b) and cryIC genes: a resistance management strategy.

Tobacco and tomato plants were generated exhibiting insect resistance due to the introduction of modified cryIA(b) and cryIC genes of Bacillus thuringiensis. Limited modifications at selected regions of the coding sequences of both genes are sufficient to obtain resistance against Spodoptera exigua, Heliothis virescens and Manduca sexta. The criteria used to modify both genes demonstrate that the removal of sequence motifs potentially resulting in premature polyadenylation and transcript instability causes increased insect resistance. The expression of a cryIC-cryIA(b) fusion resulting in protection against S. exigua, H. virescens and M. sexta demonstrates the potential of expressing translational fusions, not only to broaden the insect resistance of transgenic plants, but also to simultaneously employ different gene classes in resistance management strategies.