Resumo

OROZCO MERA, Martha Ilce; BERNAL VILLEGAS, Jaime  e  HERNANDEZ-FERNANDEZ, Javier. LSSP-PCR to identify polymorphisms in the gene cry1B of Bacillus thuringiensis native strain. Rev. colomb. biotecnol [online]. 2012, vol.14, n.1, pp.121-134. ISSN 0123-3475.

LSSP-PCR (low stringency specific primer-PCR), technique was standardized for polymorphisms in native isolates cry1B genes Bacillus thuringiensis (Bt) identify. 164 isolates were evaluated by identifying the gene colombian native cry1Ba, in 11 of these isolates. The 11 amplified fragments, along with the reference strain Bt subsp. aizawai HD137 were analyzed by LSSP-PCR and electrophoretic patterns obtained were compared qualitatively. With the amplified products with direct oligonucleotide was constructed using UPGMA dendrogram showed three clusters with similarity of 83, 79 and 68%. The group with 68% similarity corresponded to the isolation BtGC 120 native who introduced the variable pattern of bands. With the isolation BtGC 120 reverse oligonucleotide showed less variability (43%). The nucleotide sequence obtained from this fragment of 806 bp showed 93% identity with the sequence of the genes of Bt morrisoni cry1Bc1 and cry1Bb1 BT-strain EG5847. Predicted reading frame of 268 a protein amino acid residues with 88% identity with the protein Cry1Bc. This sequence revealed two domains, an N endotoxin involved in the formation of the pore and other related M endotoxin in receptor recognition. The biological evaluation BtGC120 insulation on first instar larvae of Spodoptera frugiperda insect pest, showed an LC50 of 1.896 ng of total protein per cm2. This study shows that the LSSP-PCR is a technique that identifies a specific way variation in the sequences of cry genes of Bt, with the potential to find new genes with novel biological activities.

Palavras-chave : Bacillus thuringiensis; cry1B genes; delta-endotoxins; Sodoptera frugiperda; BTGC120.

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