We used Agrobacterium tumefaciens to transform flowering stalk explants of five genotypes of broccoli with a construct containing the neomycin phosphotransferase gene and a Bacillus thuringiensis (Bt) gene [CryIA(c) type] optimized for plant expression. Overall transformation efficiency was 6.4%; 181 kanamycin-resistant plants were recovered. Of the 162 kanamycin-resistant plants tested, 112 (69%) caused 100% morality of 1st-instar larvae of a Bt-susceptible diamondback moth strain. Southern blots of some resistant transformants confirmed presence of the Bt gene. Selected plants that gave 100% mortality of susceptible larvae allowed survival of a strain of diamondback moth that had evolved resistance to Bt in the field. F1 hybrids between resistant and susceptible insects did not survive. Analysis of progeny from 26 resistant transgenic lines showed 16 that gave segregation ratios consistent with a single T-DNA integration. Southern analysis was used to verify those plants possessing a single T-DNA integration. Because these transgenic plants kill susceptible larvae and F1 larvae, but serve as a suitable host for resistant ones, they provide an excellent model for tests of Bt resistance management strategies.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Agronomy and Crop Science
- Plant Science