Interações das proteínas Cry1Ia10 e Vip3Aa de Bacillus thuringiensis e toxicidade para larvas de Spodoptera spp. (Lepidoptera: Noctuidae)
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Data
2012-06-01
Autores
Bergamasco, Vivian Boter [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
As pragas polífagas do gênero Spodoptera são consideradas algumas das mais importantes causadoras de prejuízos e de ampla distribuição em toda a América. Com o emprego intensivo de plantas geneticamente modificadas, contendo genes de Bacillus thuringiensis que codificam proteínas inseticidas, há a possibilidade do surgimento de insetos resistentes. Para driblar o desenvolvimento da resistência, podem-se utilizar plantas piramidadas expressando proteínas inseticidas com modo de ação distintas. Com essa finalidade, o presente estudo verificou o modo de ação das proteínas Cry1Ia10 e Vip3Aa sobre larvas neonatas de Spodoptera frugiperda, S. albula, S. eridania e S. cosmioides, correlacionando a interação dessas toxinas aos receptores de membrana do epitélio intestinal pela união das toxinas biotiniladas às Vesículas de Membrana da Microvilosidade Apical (VMMA) ou “Brush Border Membrane Vesicles” (BBMV) de intestino médio das larvas desses insetos. Em todas estas espécies foi detectada, por “Ligand-Blotting”, um receptor putativo de cerca de 65 kDa. Em ensaios de competição in vitro com as proteínas biotiniladas, verificou-se que Vip3Aa e Cry1Ia10 não competem pelo mesmo receptor, e que Vip3Aa é mais eficiente que Cry1Ia10, quando testadas individualmente. Quando combinadas, observou-se a ação sinérgica das toxinas para S. frugiperda, S. albula e S. cosmioides. Entretanto, para S. eridania há a competição pelo mesmo receptor, e Cry1Ia10 é mais eficiente que Vip3Aa, porém com ação antagônica, quando testadas conjuntamente. Esses resultados sugerem que o uso desses genes na obtenção de plantas piramidadas pode não vir a ser efetivo para driblar a resistência em todas as espécies do mesmo gênero de insetos-praga
Poliphagous pests belonging to the genus Spodoptera are considered some of the most important and harmfull pests due to its wide distribution over the American continent. Presently with the increase of the usage of genetically modified plants, containing Bacillus thuringiensis genes, which code for insecticide proteins, there is the possibility of the surge of resistant insects. To overcome this possibility, it has been proposed to use pyramided plants expressing toxins with different mode of action. Within mind the present study has verified the mode of action of the proteins Cry1IAa and Vip3Aa against neonate larvae of S. frugiperda, S. albula, S. eridania and S. cosmioides and the interaction between these toxins towards membrane receptors of the intestinal epithelium apical cells. It was then analyzed the biotinilated toxins union to the Brush Border Membrane Vesicles (BBMV) of the larvae from these insects. On all of them it was observed using the ligant blotting procedure a putative receptor with approximately 65 kDa in weight. Using in vitro competition assays with the biotinilated toxins, it was possible to observe that the protein Vip3Aa does not compete with the protein Cry1Ia and that the toxin Vip3Aa is more efficient than Cry1Ia when assayed individually. When analyzed together it was possible to observe a synergic action of these proteins over S. frugiperda, S. albula and S. cosmioides. However, for S. eridania it was observed competition between these two proteins (Cry1Ia and Vip3A) and a common receptor. Also for this last observation the Cry1IAa protein had a stronger action than the Vip3Aa although with antagonic action when tested together. The results seem to indicate that the use of these genes together, aiming transgenic pyramided plants may not be so effective as need to avoid the surge of resistance by the analyzed pests
Poliphagous pests belonging to the genus Spodoptera are considered some of the most important and harmfull pests due to its wide distribution over the American continent. Presently with the increase of the usage of genetically modified plants, containing Bacillus thuringiensis genes, which code for insecticide proteins, there is the possibility of the surge of resistant insects. To overcome this possibility, it has been proposed to use pyramided plants expressing toxins with different mode of action. Within mind the present study has verified the mode of action of the proteins Cry1IAa and Vip3Aa against neonate larvae of S. frugiperda, S. albula, S. eridania and S. cosmioides and the interaction between these toxins towards membrane receptors of the intestinal epithelium apical cells. It was then analyzed the biotinilated toxins union to the Brush Border Membrane Vesicles (BBMV) of the larvae from these insects. On all of them it was observed using the ligant blotting procedure a putative receptor with approximately 65 kDa in weight. Using in vitro competition assays with the biotinilated toxins, it was possible to observe that the protein Vip3Aa does not compete with the protein Cry1Ia and that the toxin Vip3Aa is more efficient than Cry1Ia when assayed individually. When analyzed together it was possible to observe a synergic action of these proteins over S. frugiperda, S. albula and S. cosmioides. However, for S. eridania it was observed competition between these two proteins (Cry1Ia and Vip3A) and a common receptor. Also for this last observation the Cry1IAa protein had a stronger action than the Vip3Aa although with antagonic action when tested together. The results seem to indicate that the use of these genes together, aiming transgenic pyramided plants may not be so effective as need to avoid the surge of resistance by the analyzed pests
Descrição
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Inseto - Larva, Espodoptero, Spodoptera eridania, Pragas agricolas, Poliphagous pests
Como citar
BERGAMASCO, Vivian Boter. Interações das proteínas Cry1Ia10 e Vip3Aa de Bacillus thuringiensis e toxicidade para larvas de Spodoptera spp. (Lepidoptera: Noctuidae). 2012. viii, 96 f. Tese (doutorado) - Universidade Estadual Paulista, Faculdade de Ciências Agrárias e Veterinárias, 2012.