Caracterização molecular e seleção de isolados de Bacillus thuringiensis com potencial inseticida para Sphenophorus levis
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Data
2007-12-19
Autores
Cícero, Elaine Aparecida Silva [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A bactéria B. thuringiensis caracteriza-se pela produção de proteínas tóxicas a representantes de diversas ordens de insetos, as quais são codificadas por genes cry. Este trabalho foi realizado com objetivo de selecionar isolados de B. thuringiensis por meio da caracterização morfológica e molecular identificando as diferentes subclasses dos genes cry3, cry7, cry8, cry9 e cry35 e determinar a patogenicidade contra Sphenophorus levis, que é uma das mais importantes pragas da cultura da cana-de-açúcar. Foram utilizados 1128 isolados de B. thuringiensis e com a observação em microscópio com contraste de fases foram confirmadas como pertencentes à espécie de B. thuringiensis e três linhagens padrões. O material genético foi extraído pela matriz de troca iônica “Instagene Matrix” e submetido a PCR com iniciadores gerais cry3, cry7, cry8, cry9 e cry35 identificando-se 45 isolados com produto de amplificação para coleópteros, os quais juntamente com as linhagens padrões de B. thuringiensis var. tenebrionis, var. morrissone e var. tolworthi e testemunhas foram utilizados para a realização do bioensaio. A análise discriminante alocou os isolados em três grupos quanto à toxicidade de B. thuringiensis e os grupos ficaram assim definidos: um grupo de BAIXA efetividade, com 19,60% do total dos isolados, nesse grupo ficaram as testemunhas e uma linhagem padrão B. thuringiensis var. morrissone e isolados do LGBBA; um grupo de MÉDIA efetividade, com 66,67% do total dos isolados, nesse grupo ficaram duas linhagens padrões B. thuringiensis var. tolworthi e var. morrissone e isolados do LGBBA e um grupo com ALTA efetividade com 13,72% do total dos isolados do LGBBA, os quais podem ser considerados promissores no controle biológico de S. levis.
Molecular characterization and selection of B. thuringiensis isolates exhibiting potential control on Sphenophorus levis larvae. Bacillus thuringiensis is characterized by the production of toxic proteins to insects from a number of different orders which are coded by the cry genes. This work was developed aiming to select B. thuringiensis isolates using morphological and molecular analysis so as to identify different cry genes subclass for cry3, cry7, cry8, cry9 and cry35 and also to determine the pathogenicity levels against Sphenophorus levis larvae, that is one of the most important sugar-cane pests. As much as 1128 bacterial isolates together with three control strains were used and for the phase contrast microscopy and molecular analysis. The genetic materials were obtained using the Instagene Matrix that is an ionic matrix and the PCR primers used were developed for cry3, cry7, cry8, cry9 and cry35 genes. A total of 45 isolates were selected showing possible amplicons for coleopterans. These isolates together with the standard strains B. thuringiensis var. tenebrionis, var. morrissone a var. tolworthi were used for bioassays. A discriminating analysis has allocated the bacterial isolates within three groups of B. thuringiensis toxicity and these groups were defined as one with LOW effectivity, comprising 19,6% of the isolates and the control strains together with one of the control strains B. thuringiensis var. morrissone. Another group has revealed a MEDIAN effectivity with a total of 66.7% of the isolates including two other control strains B. thuringiensis var. tolworthi e var. morrissone and a third group with HIGH effectivity with 13.7% of the isolates which were considered as promising B. thuringiensis isolates for the control of S. levis larvae.
Molecular characterization and selection of B. thuringiensis isolates exhibiting potential control on Sphenophorus levis larvae. Bacillus thuringiensis is characterized by the production of toxic proteins to insects from a number of different orders which are coded by the cry genes. This work was developed aiming to select B. thuringiensis isolates using morphological and molecular analysis so as to identify different cry genes subclass for cry3, cry7, cry8, cry9 and cry35 and also to determine the pathogenicity levels against Sphenophorus levis larvae, that is one of the most important sugar-cane pests. As much as 1128 bacterial isolates together with three control strains were used and for the phase contrast microscopy and molecular analysis. The genetic materials were obtained using the Instagene Matrix that is an ionic matrix and the PCR primers used were developed for cry3, cry7, cry8, cry9 and cry35 genes. A total of 45 isolates were selected showing possible amplicons for coleopterans. These isolates together with the standard strains B. thuringiensis var. tenebrionis, var. morrissone a var. tolworthi were used for bioassays. A discriminating analysis has allocated the bacterial isolates within three groups of B. thuringiensis toxicity and these groups were defined as one with LOW effectivity, comprising 19,6% of the isolates and the control strains together with one of the control strains B. thuringiensis var. morrissone. Another group has revealed a MEDIAN effectivity with a total of 66.7% of the isolates including two other control strains B. thuringiensis var. tolworthi e var. morrissone and a third group with HIGH effectivity with 13.7% of the isolates which were considered as promising B. thuringiensis isolates for the control of S. levis larvae.
Descrição
Palavras-chave
Rhizobia, Genome, Nitrogen-fixing, Simbiotic islands, Reação em cadeia de polimerase, Nitrogênio - Fixação, Genoma, Ilha simbiótica
Como citar
CÍCERO, Elaine Aparecida Silva. Caracterização molecular e seleção de isolados de Bacillus thuringiensis com potencial inseticida para Sphenophorus levis. 2007. xi, 76 f. Tese (doutorado) - Universidade Estadual Paulista, Faculdade de Ciências Agrárias e Veterinárias, 2007.