Genetic engineering of elite indica rice with cry2Ac gene to impart insect resistance

Crystal proteins from Bacillus thuringiensis ( Bt ) have potential insecticidal properties. Heterologous expression of genes encoding Cry proteins in plants can impart resistance to insects, thus, providing a sustainable and cost-effective solution for insect pest management. Therefore, we have transformed popular elite indica rice cultivar ASD16 with a construct harbouring a cry2Ac gene driven by constitutive CaMV35S promoter, selectable marker hygromycin phosphotransferase ( hpt ) gene and scorable marker gusA gene. A total of ninety-nine independent putative transgenic plants were regenerated with the transformation frequency ranging between 5 and 38%. Sixty six out of 70 putative transformants tested for the presence of cry2Ac gene by PCR were found to be positive. However, when the plants were subjected to insect bioassay, none of them showed insect mortality. This could possibly be due to undetectable level of expression of cry2Ac gene which may require optimization of GC content and use of suitable promoters to drive the expression of transgenes.