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Master's Dissertation
DOI
10.11606/D.87.2008.tde-12012009-114036
Document
Author
Full name
Luciana Aparecida Avila
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2008
Supervisor
Committee
Melo, Itamar Soares de (President)
Azevedo, Joao Lucio de
Capalbo, Deise Maria Fontana
Title in Portuguese
Efeitos do algodão Bt (Bollgard evento 531) na comunidade bacteriana da rizosfera.
Keywords in Portuguese
Pseudomonas
DGGE
Ecologia microbiana
Microbiologia do solo
Plantas geneticamente modificadas
Proteína Cry
Abstract in Portuguese
O algodão transgênico Bollgard® (algodão Bt) contém o gene cry1Ac da bactéria Bacillus thuringiensis, que confere a planta resistência a Lepidopteros. A expressão deste gene na planta pode acarretar efeitos ecológicos adversos à microbiota do solo e da rizosfera. Em casa-de-vegetação, a comunidade bacteriana associada ao algodão Bt foi comparada a do algodão convencional, em dois tipos de solos e quatro estádios fenológicos. Amostras de rizosfera foram avaliadas por técnicas dependentes e independentes de cultivo. As técnicas de contagem de bactérias e DGGE permitiram observar os efeitos do algodão Bt na densidade e diversidade de Pseudomonas e bactérias totais, durante os estádios iniciais de desenvolvimento da planta. A toxina Cry foi detectada na rizosfera de algodão Bt, em todo ciclo da cultura. Nas fases de formação do botão floral e abertura das maçãs, a atividade microbiana foi maior na rizosfera do algodão Bt. Esses resultados indicam o potencial do ambiente rizosférico em reestabelecer à estrutura da comunidade bacterina após um impacto temporal.
Title in English
Effect of Bt cotton (Bollgard event 531) on the bacterial community of the rhizosphere.
Keywords in English
Pseudomonas
Cry protein
DGGE
Genetically modified plant
Microbial ecology
Soil microbiology
Abstract in English
The transgenic cotton Bollgard® (Bt cotton) contains the cry1Ac gene from the Bacillus thuringiensis bacterium, which confers the plant resistance against some insects. The expression of this gene in the plant can cause adverse ecological effects on soil and rhizosphere microbiota. In a greenhouse experiment, the bacterial community associate to Bt cotton was compared to non-transgenic parental cultivar plants, in two types of soil at different plant development stages. Rhizosphere communities were evaluated by culture-dependent and independent approaches. Results reveal the effect of the Bt cotton in the density and diversity of Pseudomonas and total bacteria, during initial plant development stages. The Cry toxin was detected in the rhizosphere of Bt cotton, during all plant cycle. In the phases of flower formation and fruit opening, the microbial activity was greater in the rhizosphere of Bt cotton. These results show the potential of the rhizosphere to reestablish the original structure of the bacterial community after a temporary impact.
 
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Publishing Date
2009-03-02
 
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