Diversidade e prospecção de rizobactérias associadas à cana-de-açúcar sob manejo orgânico: metodologias clássicas e moleculares a serviço da agroecologia

• Autor(a) principal: Rodrigues, Ariana Alves
• Data de Publicação: 2018
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/9681
• topic: Rizobactérias; Tradicional; Orgânico; Diversidade; PCV; Rhizobacteria; Traditional; Organic; Diversity; PGP; ENGENHARIA TERMICA::CONTROLE AMBIENTAL

The current way of sugarcane cultivation leads to the reduction of biodiversity and generates a series of environmental impacts. Thinking about the environmental issue, several strategies have been developed to make this crop less harmfull to the environment and one of these strategies refers to organic farming. The microorganisms associated with organic management are essential in the transformation and release of nutrients to plants. Among the microorganisms associated with organic cultivation, plant growth promoting rhizobacteria (PGPR) can promote plant growth in processes such as biofertilization, biostimulation and biocontrol. The present study aimed to evaluate the diversity and metabolic potential of rhizospheric communities associated with sugarcane under organic management, prospect PGPR associated with sugarcane and evaluate in vitro their potential to promote plant growth. Samples of sugarcane rhizosphere, variety CTC4, cultivated under organic and traditional management, had their DNA extracted and sequenced. The sequences obtained were analyzed with the mothur software and the alpha diversity was accessed with the Shannon and Chao1 metrics. The beta diversity was verified with the Bray-Curtis index and with principal coordinates analysis (PCoA). The functional potential of communities was predicted with the PICRUSt software. For microbial prospecting, rhizospheric microorganisms of the varieties IAC 911099 and CTC4, cultivated under organic management, were isolated. The diazotrophic rhizobacteria were isolated in NFB and Burk medium, and the actinobacteria in ISP and SCA medium. The isolated microorganisms were screened in vitro for plant growth promotion traids such as indole-acetic acid (IAA), phosphate solubilization, nitrogen fixation, ammonia production, hydrogen cyanide (HCN) production, cellulases production, chitinase production and for Fusarium moniliforme antagonism. The alpha diversity did not change due to management (p> 0.05), however, differences in the beta diversity were observed between organic and conventional samples. In relation to functional analysis, in the two places analyzed, the genes related to nitrogen fixation were more expressed in farms under organic cultivation. Of the microorganisms prospected, 81 were fast-growing diazotrophic and 21 actinobacteria. These microorganisms were distributed in 14 genera. Of these, 45.6% of the fast-growing diazotrophic and 29% of the actinobacteria were able to fix nitrogen. In addition, were found bacteria capable of producing IAA, solubilizing phosphate, producing ammonia, cellulases and chitinases. Members of Burkholderia and Streptomyces were able to inhibit the growth of phytopathogenic fungus F. moniliforme. The prospected microorganisms present potential as inoculants in the biofertilization, biostimulation and biocontrol processes and it is suggested the use of bacteria of the genus Burkholderia and the genus Streptomyces for their abilities to promote biocontrol, together with bacteria of the genus Sphingobium and Rhizobium that have abilities to promote plant growth through nitrogen fixation, phosphate solubilization and IAA production.