A chimeric protein encoded by synthetic genes shows toxicity to Helicoverpa armigera and Spodoptera littoralis larvae
2013
Abbas, Z. (PARC Inst. of Advanced Studies in Agriculture, NARC, Islamabad (Pakistan). Dept. of Plant Genomics and Biotechnology) | Zafar, Y. (Pakistan Atomic Energy Commission, Islamabad (Pakistan). Biosciences Div.) | Khan, S.A. (National Inst. for Biotechnology and Genetic Engineering, Faisalabad (Pakistan)) | Mukhtar, Z.
Insects have natural potential to develop resistance against chemical insecticides. Several resistance strategies have been suggested including biopesticides and use of two dissimilar toxins. Advances in molecular biology techniques have now allowed construction of chimerical proteins to delay the development of resistance in insect population, but still there are chances of developing resistance in insect population against them as these fusions are based on Bacillus thuringiensis (Bt) genes only, which have some homology in their amino acid sequences, having same mode of action and derived from same bacterial origin. In the present study omega-ACTX-Hv1a toxin gene (Hvt) as an insect calcium channel antagonist is fused with Bt cry/Ac to combine both strategies (biopesticides and two dissimilar toxins) and delay the resistance in insect population. The recombinant protein has been successfully expressed in prokaryotic system and was detected by SDS PAGE. Topical application of the 1.0 pmol purified recombinant protein to the thoracic region paralyzed and immobilized the Helicoverpa armigera and Spodoptera littoralis larvae within 2 h, 100% mortality was observed in insects after 24 h. The LD50 was found to be 4 and 2 pmol per gram of body weight for H. armigera and S. littoralis larvae, respectively. The present study clearly indicates that this recombinant protein is highly effective against agronomical important lepidopteron insects and is an excellent candidate for use as a biopesticides or expressed heterogeneously in agricultural crops to provide long lasting resistance to insect attacks.
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