Entomocidal Activity of Bacillus Thuringiensis Transgenic Rice Plants Against Rice Leaffolder, Cnaphalocrocis Medinalis (Lepidoptera: Pyralidae).
Transgenic rice plants obtained through the incorporation of Bt cry1Ac gene. Initially putative transformants were screened for pesticidal activity against rice leaf folder larvae. Selected putative transformants showed a range of larval mortality from 20-100 percent to C. medinalis. The integration of the Bt cry gene was checked by Polymerase Chain Reaction (PCR), using primers 5` ACA GAA GAC CCT TCA ATA TC 3` and 3` GTT ACC GAG TGA AGA TGT AA 5` for amplification of a 656 bp fragment of DNA from the genomic DNA of putative transformants. Selection based on PCR and initial bioassays, two transgenic plants designated as, CAMB 1148 and CAMB 1150 were further confirmed for toxin expression by ELISA, Western blot analysis and comparative biotoxicity assay. ELISA and Western blot were performed with polyclonal antibody of Cry1Ac toxins that showed the presence of active ingredient of Bt toxin in both plants. Biotoxicity assays also reconfirmed the stability and activity of Cry toxins in both transgenic rice plants, eventually aiming for homozygosity with enhanced resistance to rice leaf folder.
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