author(s)
Kaviyapriya M, RA Lone, Balakrishnan N, Rajesh S and Ramalakshmi A

abstract
Bacillus thuringiensis (Bt), Gram-positive, spore forming bacterium produces insecticidal proteins during vegetative phase or sporulation phase which are toxic to a wide range of insects and are encoded by cry and vip genes. Identification of genes encoding insecticidal protein is important and will be useful in generating insect resistance transgenic plants. In this present study, an indigenous Bt isolate T29 was characterized and the lepidopteran toxic proteins encoding genes were cloned. The colony of Bt isolate (T29) was creamy white in colour with fried egg type and circular in shape with serrate margin and the isolate had bipyramidal and cuboidal shaped parasporal inclusions. Bioassay studies with spore-crystal mixture of T29 Bt isolate showed 100 per cent mortality against the invasive pest Fall armyworm Spodoptera frugiperda. SDS-PAGE analysis revealed the presence of two insecticidal crystal proteins with molecular weight of ~130 kDa (Cry1) and ~65 kDa (Cry2). The isolate showed the presence of cry1, cry2Aa and vip3A genes while screening by polymerase chain reaction (PCR) using gene specific primers. The lepidopteran toxic genes viz., cry1Ac (truncated), cry2Aa (full length) and vip3A (partial) genes were cloned and sequenced.