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KMID : 0380220070400050773
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Journal of Biochemistry and Molecular Biology
2007 Volume.40 No. 5 p.773 ~ p.782
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Susceptibility of Anthonomus grandis (Cotton Boll Weevil) and Spodoptera frugiperda (Fall Armyworm) to a Cry1Ia-type Toxin from a Brazilian Bacillus thuringiensis Strain
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Grossi-de-Sa Maria Fatima
Magalhaes Mariana Quezado de
Silva Marilia Santos
Silva Shirley Margareth.Buffon
Dias Simoni Campos
Nakasu Erich Yukio Tempel
Brunetta Patricia Sanglard Felipe
Oliveira Gustavo Ramos
Neto Osmundo Brilhante de Oliveira
Oliveira Raquel Sampaio de
Soares Luis Henrique Barros
Ayub Marco Antonio Zachia
Siqueira Herbert Alvaro Abreu
Figueira Edson L.Z.
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Abstract
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Different isolates of the soil bacterium Bacillus thuringiensis produce multiple crystal (Cry) proteins toxic to a variety of insects, nematodes and protozoans. These insecticidal Cry toxins are known to be active against specific insect orders, being harmless to mammals, birds, amphibians, and reptiles. Due to these characteristics, genes encoding several Cry toxins have been engineered in order to be expressed by a variety of crop plants to control insectpests. The cotton boll weevil, Anthonomus grandis, and the fall armyworm, Spodoptera frugiperda, are the major economically devastating pests of cotton crop in Brazil, causing severe losses, mainly due to their endophytic habit, which results in damages to the cotton boll and floral bud structures. A cry1Ia-type gene, designated cry1Ia12, was isolated and cloned from the Bt S811 strain. Nucleotide sequencing of the cry1Ia12 gene revealed an open reading frame of 2160 bp, encoding a protein of 719 amino acid residues in length, with a predicted molecular mass of 81 kDa. The amino acid sequence of Cry1Ia12 is 99% identical to the known Cry1Ia proteins and differs from them only in one or two amino acid residues positioned along the three domains involved in the insecticidal activity of the toxin. The recombinant Cry1Ia12 protein, corresponding to the cry1Ia12 gene expressed in Escherichia coli cells, showed moderate toxicity towards first instar larvae of both cotton boll weevil and fall armyworm. The highest concentration of the recombinant Cry1Ia12 tested to achieve the maximum toxicities against cotton boll weevil larvae and fall armyworm larvae were 230 &mgr;g/mL and 5 &mgr;g/mL, respectively. The herein demonstrated insecticidal activity of the recombinant Cry1Ia12 toxin against cotton boll weevil and fall armyworm larvae opens promising perspectives for the genetic engineering of cotton crop resistant to both these devastating pests in Brazil.
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KEYWORD
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Anthonomus grandis, Bt toxin, Coleoptera, Cotton, Cry1Ia, E. coli expression, Lepidoptera, Spodoptera frugiperda
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