Transgenic Insect-resistant Rice Expressing Both Cry1Ab And Cry2Ab

Bacillus thuringiensis (Bt) is one of the most important insect pathogens in agriculture. Bt produces insecticidal crystal proteins, which are toxic to many pests specifically. The transgenic plants based on Bt insecticidal toxins have been commercialized world-widely for nearly three decades. With the wide utilization of insect-resistant transgenic plants, the development of insect resistance to Bt toxins is a major concern. Previous studies demonstrated that transgenic crops utilized two or more Bt insecticidal genes with different modes of action will greatly delay of the development of Bt resistance, compared just using one toxin.Cry1Ab and Cry2Ab share very low identity in amino acid sequence and they are likely to have different modes of action in killing insect pests. In this paper a transformation vector,1300-cry1Ab-cry2Ab-1174, was constructed to contain three expression cassettes in its T-DNA, cry1Ab, cry2Ab and the glyphosate resistance EPSPS gene,1174. About 30 transgenic rice events were obtained via Agrobacterium-mediated transformation.PCR and Southern hybridization analysis of the transgenic rice plants showed that the insect-resistant genes as well as the EPSPS gene have been successfully transferred into rice. Western Blot analysis indicated that cry1Ab,cry2Ab and glyphosate-resistant gene 1174 were all expressed successfully in transgenic rice leaves. Bioassays with cotton bollworm and rice leaf roller demonstrated that these transgenic plants were highly resistance to insects. The transgenic rice plants were also found to be highly tolerant to 20mM/L glyphosate in green house.