'Composicao Revista de Ciencias Sociais da Universidade Federal de Mato Grosso do Sul'
Abstract
The death syndrome of marandu grass (Brachiaria brizantha) is one of the main problems in the degradation of pastures in the Amazon biome. Plant death occurs during the rainy season due to susceptibility to phytopathogens. Thus, the objective was to study production systems and select bacteria antagonistic to Fusarium spp., one of the phytopathogenic agents. Bacterial isolates were obtained from 10 production systems, native forest and fallow, in rain and drought season. Molecular characterization of isolates was carried out by sequencing. Two Fusarium isolates were assessed. For pathogen 1, in the rainy season, 7.5% of the isolates showed antagonism, while in the dry season it was 15%. For pathogen 2, not all isolates positive for pathogen 1 were efficient in the control, showing correlations between bacterial isolates and Fusarium spp. In the rain, for pathogen 1, the forest showed the highest number of positive isolates (20%). In the dry season, the treatments forest, 1-Forest and 8-plant-forest integration for pathogen 1, were ones with the highest number of positives (25%). In the molecular identification, 8 bacterial genera were found: Burkholderia, Bacillus, Brevibacillus, Streptomyces, Pseudomonas, Escherichia, Paenibacillus and Pandoraea, most of which are described as able to controlling Fusarium spp. in vitro.
Keywords: Burkholderia, biological control, Integrated crop-livestock-forest.A síndrome da morte do capim-marandu (Brachiaria brizantha) é um dos principais problemas na degradação das pastagens no bioma Amazônia. A morte das forrageiras ocorre durante a época chuvosa por suscetibilidade a fitopatógenos. Assim, objetivou-se estudar sistemas de produção e selecionar bactérias antagônicas a Fusarium spp., um dos agentes fitopatogênicos. Os isolados bacterianos foram obtidos de 10 sistemas de produção, mata nativa e pousio, na chuva e na seca. Realizou-se a caracterização molecular de isolados por sequenciamento. Dois isolados de Fusarium foram testados. Para o patógeno 1, na época da chuva, 7,5% dos isolados apresentaram antagonismo enquanto na seca foi 15%. Para o patógeno 2, nem todos os isolados positivos para o patógeno 1 foram eficientes no controle, demonstrando a ocorrência de interações entre isolados bacterianos e Fusarium spp. Na chuva, para o patógeno 1, a mata apresentou maior número de isolados positivos (20%). Na seca, os tratamentos mata, 1-Floresta e 8-integração lavoura floresta para o patógeno 1, foram os que apresentaram maior número de positivos (25%). Na identificação molecular, 8 foram os gêneros bacterianos encontrados: Burkholderia, Bacillus, Brevibacillus, Streptomyces, Pseudomonas, Escherichia, Paenibacillus e Pandoraea, em que a maioria é descrita como capaz de controlar Fusarium spp. in vitro.
Palavras-chave: Burkholderia; controle biológico; integração lavoura-pecuária-floresta.
Biodiversity of bacteria antagonic to fungi associated with syndrome's death palisadegrass (Brachiaria brizantha)
ABSTRACT: The death syndrome of marandu grass (Brachiaria brizantha) is one of the main problems in the degradation of pastures in the Amazon biome. Plant death occurs during the rainy season due to susceptibility to phytopathogens. Thus, the objective was to study production systems and select bacteria antagonistic to Fusarium spp., one of the phytopathogenic agents. Bacterial isolates were obtained from 10 production systems, native forest and fallow, in rain and drought season. Molecular characterization of isolates was carried out by sequencing. Two Fusarium isolates were assessed. For pathogen 1, in the rainy season, 7.5% of the isolates showed antagonism, while in the dry season it was 15%. For pathogen 2, not all isolates positive for pathogen 1 were efficient in the control, showing correlations between bacterial isolates and Fusarium spp. In the rain, for pathogen 1, the forest showed the highest number of positive isolates (20%). In the dry season, the treatments forest, 1-Forest and 8-plant-forest integration for pathogen 1, were ones with the highest number of positives (25%). In the molecular identification, 8 bacterial genera were found: Burkholderia, Bacillus, Brevibacillus, Streptomyces, Pseudomonas, Escherichia, Paenibacillus and Pandoraea, most of which are described as able to controlling Fusarium spp. in vitro.
Keywords: Burkholderia; biological control; integrated crop-livestock-forest
