Stacked insecticidal genes in potatoes exhibit enhanced toxicity against Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)

The present study was performed to express stacked insecticidal genes in potato cv. Lady Olympia and Agria to encode resistance against Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say). Bacillus thuringiensis (Bt) gene ( cry3A ), synthetic hybrid ( SN-19 ) and plant proteinase inhibitor Oryza cystatin II ( OCII ) cloned in pCAMBIA1301 binary vector in two different combinations as of DS-1 ( cry3A + SN-19 genes) and DS-2 ( OCII + SN-19 genes) constructs and further transformed to two potato cultivars using Agrobacterium- mediated transformation. All molecular analyses confirmed gene integration and expression in a total of 27 primary transformants in both Agria and Lady Olympia. Insecticidal effects of T0 progeny transgenic potato plants were tested against CPB under laboratory conditions. Transgenic plants of Agria and Lady Olympia transformed with DS-1 and DS-2 constructs caused 100% mortality to all larval stages and adults of CPB. However, 100% mortality of tested insects took a longer time in the adult stage (10–14 days) compared to larval stages (2–6 days). Foliage consumption by L2-L4 larval stages and adults of CPB was significantly reduced in Agria and Lady Olympia plants transformed with DS-1 and DS-2 constructs, as compared to their control plants. Lower foliage consumption of transgenic plants by L1 larval stages was also observed, but the reduction was only statistically significant for some of the tested plants. These promising results indicate that the transgenic potato plants exhibit a high potential in controlling CPB population and are a useful tool in the management of imidacloprid-resistant CPB.