CLONING OF A CRYIIIA ENDOTOXIN GENE OF BACILLUS-THURINGIENSIS VAR TENEBRIONIS AND ITS TRANSIENT EXPRESSION IN INDICA RICE

Damage caused to rice production by coleopteran insects like rice weev il (Sitophilus oryzae), a stored grain insect pest and rice hispa (Dic ladispa armigera), a pest of the growing plant is quite high. In order to combat the damage, generation of insect resistant transgenic rice plant was considered desirable. CryIIIA endotoxin of Bacillus thuringi ensis var. tenebrionis, a 65 kDa protein toxic to coleopteran insects, figured as the candidate gene product. Thus, the cryIIIA gene was iso lated from a local isolate of Bacillus thuringiensis var. tenebrionis. The gene was tailored at the N-terminal end to its minimal size by us ing a synthetic ATG codon which replaced the first codon next to ATG o f threonine to proline. This modification did not affect the functiona l property of the gene product. A chimeric construct of the modified c ryIIIA gene was developed containing CaMV35S promoter and nos terminat or for plant expression. The expressibility of the cryIIIA gene in ind ica rice was judged through test for transient expression in indica ri ce protoplasts.