Molecular evaluation of Bacillus thuringiensis isolates from the soil and production of transgenic tomato plants harboring Bt gene for controlling lepidopterous insects in Egypt

Nesreen Mohammed Abd El-Ghany
Department of Entomology, Ain Shams University
January, 2011
 

Abstract
This study has two main approaches. Firstly, search for indigenous Bacillus thuringiensis strains from Egyptian soils was made and the activity was evaluated against Spodoptera littoralis, and Helicoverpa (=Heliothis) armigera. Different techniques were adopted for molecular characterization of these isolates. In a second approach, transgenic tomato (cv. Money maker) over expressing Bt gene was produced using Agrobacterium-mediated transformation method. For this, a rapid and efficient regeneration system via direct shoot organogenesis has been developed. The developed tissue culture system was used for the production of transgenic plants. Several parameters affecting Agrobacterium-mediated transformation (bacterial densities, type of explants, co-cultivation durations and pre-culture periods) were optimized. Molecular analysis confirmed the expression and integration of the transgene into tomato genome. The potential of feeding larvae of S. littoralis, H. armigera and Phthorimaea operculella on Bt tomato transgenic plants was determined and the effect caused to the predator Chrysoperla carnea (Stephens) when fed on lepidopterous insects treated with transformed plants was determined. Histopathological effects caused after feeding on transformed tomato plants compared to those caused after treatment with Bt endotoxin were carried out using Transmission Electron Microscopy (TEM).