Combining engineered (Bt-cry3A) and natural resistance mechanisms in potato (Solanum tuberosum L.) for control of the Colorado potato beetle (Leptinotarsa decemlineata Say)

The Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), is a destructive pest of the cultivated potato, Solanum tuberosum L. (2n = 4x = 48), in north central and eastern North America, Europe, and Asia. Combining the resistance mechanisms of leptine glycoalkaloids and glandular trichomes with the synthetic Bacillus thuringiensis (Bt) cry3A gene in potato may be an effective strategy for controlling the Colorado potato beetle. The objectives of this study were: (1) transform a high leptine-expressing diploid, a glandular trichome line, and a susceptible cultivar with a synthetic Bt-cry3A gene; (2) characterize the insertion and transcription of the Bt-cry3A in the transgenic lines; and (3) conduct detached-leaf bioassays of the transgenic lines to evaluate inhibition of feeding by Colorado potato beetle. Bt-cry3A transgenic plants were developed for three different potato lines (USDA8380-1 (2x), NYL235-4, and Yukon Gold). Polymerase chain reaction, and Southern and northern blot analyses confirmed integration and transcription of the cry3A gene in the transgenic lines. Detached-leaf bioassays of the cry3A engineered transgenic lines demonstrated that resistance was effective in controlling feeding by first instar Colorado potato beetles. Pyramiding natural host plant resistance mechanisms in potato with Bt, in concert with integrated management techniques, should enhance the efficacy and sustainability of control of Colorado potato beetle in commercial potato production.