Colonização de Brasilonema octagenarum UFV-E1 (Cyanobacteria) sobre plantas jovens de eucalipto e a identificação de substâncias bioativas

• Autor(a) principal: Franco, Maione Wittig
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2517
• topic: Biofilmes; Cianobactérias; Eucalyptus spp; Biofilms; Cyanobacteria; Eucalyptus spp; CNPQ::CIENCIAS BIOLOGICAS::BOTANICA

Cyanobacteria produces a wide variety of biological compounds of economic-industrial interest, often referred to as "bioactive molecules". This is a broad term that include substances, which at low concentrations, are able to affect vital metabolic processes. Recently, a new species of cyanobacteria, Brasilonema octagenarum UFV-E1, was identified. The cyanobacteria was found forming a dense biofilm covering the aerial parts of young plants of Eucalyptus spp on a clonal plant nursery. The aim of this study was to investigate the consequences of B. octagenarum colonization, on morphological, biochemical, and growth traits of young plants of Eucalyptus urograndis. The experiments were carried out under humidity and temperature controlled conditions. A cellular suspension of B. octagenarum was applied over the aerial parts of young plants. The control group consisted of non inoculated plants. Thirty days after the inoculation, the formation of scattered colonies over the leaf was observed. There was a decrease of 19% in the chlorophyll a / b ratio in the leaf areas beneath the colonies. There was no significant difference in the content of pigments (chlorophyll a, b and carotenoids). The plants responded positively to the colonization, with increase of dry mass production, mainly of the stem and root. The increase of the root and stem dry mass of colonized plants were significantly higher compared to the control group (19 and 23%, respectively). Neither anatomic alterations nor an increase in the production of total phenolic compounds were observed. During the duration period of the experiment, which compromised the initial stages of colonization, B. octagenarum colonized the aerial part of the plant without damaging it, establishing an epiphytism relation. The effects of bioactive compounds by B. octagenarum, as stimuli to plant growth, such auxin, was tested by means of a bioassay, and the influence of this cyanobacteria species colonization on rooting process of E. urophylla and E. urograndis mini-cuttings was investigated. The extract of B. octagenarum cells was analyzed in liquid chromatography coupled to mass spectrometer, LC-MS/MS. Mini-cuttings of E. urophylla and E. urograndis were inoculated with a concentrated solution of B. octagenarum cells. There was a significant increase in dry mass in the roots (31%), and in the stem (44%) in the E. urophylla. Throught the LC-MS/MS analyses, indol acetic acid (IAA) was identified, has 175 Da. The colonization of B. octagenarum in Eucalyptus urograndis, under the conditions of this study, stimulated the growth of plants, possibly in response to the IAA production. It was demonstrated that B. octagenarum produces the auxin indol acetic acid, and that this cyanobacteria has the potential to be used in developing techniques of vegetative propagation of eucalyptus plants.