Genetic engineering provides the possibility of expressing pest-resistant genes in transgenic plants. The pyramiding gene in plants is suggested to be a sustainable method for addressing pest resistance. To enhance resistance to tomato fruit borer (Helicoverpa armigera), tomato plants were transformed by pPZPY122:MPI:cry1Ac and pPZPY122:MPI:cry1Ab recombinant constructs. Bioassays on larvae consuming the single- and dual-gene transgenic tomatoes revealed that the cry1Ab/cry1Ac transgenic tomatoes could significantly improve resistance to the pest compared to the control and single-gene transgenic tomatoes. Mortality rates for larvae in single-gene plants expressing cry1Ab and cry1Ac were 36% and 47%, respectively. The cry1Ab/cry1Ac transgenic tomatoes demonstrated a 51% and 36% reduction in damage compared to cry1Ab and cry1Ac, as well as a 29% and 19% increase in larval mortality. The catalase and superoxide dismutase enzyme levels in the larvae feeding on the cry1Ab/cry1Ac plants significantly increased compared to those on the single-gene Bt. The rise in antioxidant enzyme activity is likely associated with heightened levels of Bt toxin in the larvae. It is concluded that the simultaneous expression of the cry1Ac and cry1Ab genes in tomatoes produces a synergistic effect of the Cry protein, notably increasing its lethality against the tomato fruit borer.
