Transformed tobacco with Bacillus thuringiensis cry1Aa active toxin gene and its entomocidal activity

The N terminal truncated sequence encoding 609 amino acids of the active toxin of the cry1Aa gene from Bacillus thuringiensis was cloned by PCR, and was used for tobacco transformation. Twenty independent transgenic tobacco lines with hygromycin resistance were obtained via Agrobacterium-mediated transformation. T₁ progeny seeds were germinated on medium with the segregation of hygromycin resistance and further analyzed by PCR to confirm the integration of the trans-genes into tobacco genome. Western blotting analysis of T₁ plants indicated that the cry1Aa active protein with the size of 75.6 kD was produced in transgenic tobacco leaf tissues. The entomocidal bioassay with the neonate larvae of Spodoptera exigua and Helicoverpa armigera showed that the transformed plants reached more than 60% average mortality against Helicoverpa armigera larvae, and 70% average mortality against Spodoptera exigua larvae, with the highest mortality rate of 90%. The transgenic plants also showed inhibition to the growth and development of neonate larvae of both insects.