Technical Abstract: Plant breeding has been a major force in the development of new and improved cultivars of major agriculture crops. The combination of tissue culture and molecular biology holds great potential for genetic improvements of crop plants. Bacillus thuringiensis is a soil bacterium that produces proteins that have insecticidal activity. Specific genes that code for delta endotoxin proteins have been identified and sequenced. The delta endotoxin was first expressed in transgenic tobacco (Nicotiana tabacum) plants and provided resistance to tobacco hornworm (Manduca sexta). Subsequently, various delta endotoxin genes have been sequenced and expressed in transgenic cotton (Gossypium hirsutum), corn (zea maize), potato (Solanum tuberosum), eggplant (Solanum melongena), tomatoe (Lycopersicon spp.), soybean (Glycine max), rice (Oryza savita), and poplar (Populus nigra). These transgenic crop plants control a number of economic pest that attack these crop species. Transgenic cultivars should not be thought of as stand alone products but as the foundation on which to build crop management strategies.