Expressão dos genes Vip3Aa e Cry1Ia em Escherichia coli efetivos no controle de Spodoptera frugiperda
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Data
2011-06-14
Autores
Mendes, Deise Reis de Paula [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Proteínas inseticidas derivadas de Bacillus thuringiensis (Bt) são os inseticidas biológicos mais amplamente utilizados. O trabalho teve por objetivo avaliação da toxicidade das proteínas de Bt, Cry1Ia e Vip3Aa, expressas em Escherichia coli BL21 (DE3), a fim de verificar a eficiência destas toxinas na mortalidade de Spodoptera frugiperda. Para tanto, empregou-se um par de iniciadores específicos para amplificar o fragmento correspondente ao gene vip3Aa completo contendo 2370 pb. O fragmento obtido foi clonado no vetor pET SUMO e transformado em células de E. coli BL21 (DE3) por choque térmico. A expressão das proteínas Vip3Aa e Cry1Ia previamente clonado, foi induzida por tiogalactopiranosídeo de isopropila (IPTG), e as proteínas recombinantes com peso molecular de, aproximadamente, 100 e 81 KDa respectivamente, foram detectadas por SDS-PAGE e Western Blot. Para avaliação da toxicidade os bioensaios foram realizados com as lagartas de primeiro instar que foram alimentadas com dietas artificiais contendo, na superfície, cinco diferentes concentrações da toxina Cry1Ia e cinco diferentes concentrações da toxina Vip3Aa recombinante. Os bioensaios foram estabelecidos em delineamento inteiramente casualizado, com 16 lagartas por repetição, totalizando 4 repetições por tratamento. A quantificação de lagartas mortas pela ação do B. thuringiensis, foi determinada pela CL50. Os resultados demonstraram a eficiência do sistema bacteriano na expressão das proteínas Vip3Aa e Cry1Ia de B. thuringiensis, resultando em toxinas recombinantes com elevada toxicidade frente às lagartas de S. frugiperda, o que sugere o uso destes genes na obtenção de plantas transgênicas, únicas ou piramidada, resistentes a esta praga
Insecticidal proteins derived from Bacillus thuringiensis (Bt) are the most widely used biological insecticides. The study aimed to evaluate the toxicity of Bt proteins, Cry1Ia Vip3Aa and expressed in Escherichia coli BL21 (DE3) to verify the efficiency of these toxins on the mortality of Spodoptera frugiperda. For this we used a pair of specific primers to amplify the fragment corresponding to the gene vip3Aa complete containing 2370 bp. The fragment was cloned into pET SUMO vector and transformed into cells of E. coli BL21 (DE3) by heat shock. The expression of proteins Vip3Aa and Cry1Ia previously cloned, was induced by isopropyl tiogalactopiranosídeo (IPTG), and the recombinant proteins with a molecular weight of approximately 100 and 81 kDa respectively, were detected by SDS-PAGE and Western blot. To evaluate the toxicity bioassays were performed with first instar caterpillars that were fed diets containing artificial, in surface, whit five different toxin concentrations of Cry1Ia and five different concentrations of recombinant toxin Vip3Aa. Bioassays were established in a randomized design, with 16 larvae per repetition, totaling four replicates per treatment. The quantification caterpillar dead by the action of B. thuringiensis, was determined by LC50. The results demonstrated the efficiency of the bacterial system in protein expression Vip3Aa Cry1Ia of B. thuringiensis toxins, resulting in recombinants with high toxicity against the larvae of S. frugiperda, suggesting the use of these genes in the production of transgenic plants, single or pyramided resistant to this pest
Insecticidal proteins derived from Bacillus thuringiensis (Bt) are the most widely used biological insecticides. The study aimed to evaluate the toxicity of Bt proteins, Cry1Ia Vip3Aa and expressed in Escherichia coli BL21 (DE3) to verify the efficiency of these toxins on the mortality of Spodoptera frugiperda. For this we used a pair of specific primers to amplify the fragment corresponding to the gene vip3Aa complete containing 2370 bp. The fragment was cloned into pET SUMO vector and transformed into cells of E. coli BL21 (DE3) by heat shock. The expression of proteins Vip3Aa and Cry1Ia previously cloned, was induced by isopropyl tiogalactopiranosídeo (IPTG), and the recombinant proteins with a molecular weight of approximately 100 and 81 kDa respectively, were detected by SDS-PAGE and Western blot. To evaluate the toxicity bioassays were performed with first instar caterpillars that were fed diets containing artificial, in surface, whit five different toxin concentrations of Cry1Ia and five different concentrations of recombinant toxin Vip3Aa. Bioassays were established in a randomized design, with 16 larvae per repetition, totaling four replicates per treatment. The quantification caterpillar dead by the action of B. thuringiensis, was determined by LC50. The results demonstrated the efficiency of the bacterial system in protein expression Vip3Aa Cry1Ia of B. thuringiensis toxins, resulting in recombinants with high toxicity against the larvae of S. frugiperda, suggesting the use of these genes in the production of transgenic plants, single or pyramided resistant to this pest
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Palavras-chave
Pragas agricolas - Controle biologico, Toxinas, Lepidoptero, Bioensaios, Biological control, Bioassays, BT toxins, Lepdoptera
Como citar
MENDES, Deise Reis de Paula. Expressão dos genes Vip3Aa e Cry1Ia em Escherichia coli efetivos no controle de Spodoptera frugiperda. 2011. ix, 59 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Ciências Agrárias e Veterinárias, 2011.