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 Bacill us thuringiensis. Limited modifications at selected regions of the cod ing sequences of both genes are sufficient to obtain resistance agains t Spodoptera exigua, Heliothis virescens and Manduca sexta. The criter ia used to modify both genes demonstrate that the removal of sequence motifs potentially resulting in premature polyadenylation and transcri pt instability causes increased insect resistance. The expression of a cryIC-cryIA(b) fusion resulting in protection against S. exigua, H. v irescens and M. sexta demonstrates the potential of expressing transla tional fusions, not only to broaden the insect resistance of transgeni c plants, but also to simultaneously employ different gene classes in resistance management strategies.