Rudgea viburnoides (Cham) Benth. (Rubiaceae): acúmulo de alumínio, composição mineral e metabolismo antioxidativo em diferentes fitofisionomias de Cerrado

• Autor(a) principal: Malta, Priscila Gonçalves
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2570
• topic: Rudgea viburnoides; Plantas - Efeito dos minerais; Plantas - Nutrição; Alumínio; Rudgea viburnoides; Plants - Effect of minerals; Plants - Nutrition; Aluminum; CNPQ::CIENCIAS BIOLOGICAS::BOTANICA

The acidiy of soils allows the aluminum (Al) becomes available to plants can induce toxic effects on the metabolism. However, the native plants of Cerrado can survive in acid soils with high concentrations of Al, presenting mechanisms of tolerance to this metal. The Ruhiaccac family is well represented in the biome and is one of the most representative lamin with Al accumulating species. The study proposed to evaluate the distribution of Al in the tissues of Rudgea viburnoides (Rubiaceae); analyze the effects of different soil Cerrado National Forest (FLONA) of Paraopeba, MG, on the nutritional profile and metal accumulation in the plant and to identify possible defense mechanisms present in this Al tolerant species. To investigate the chemical composition of the soil in live different areas in FLONA (cerrado sensu striclo on Yellow Latosol - Css LA; on Yellow Red Latosol - Css LVA; on Yellow Cambisol - Css Cxb and areas of dystrophic and mesotrophic Cerradão CD and CM on Red Latosol), samples were randomly collected at depths of 0-20, 20 40 and 40-60 cm with three replications. Different techniques were used to Al histolocalization in vegetative organs of R. viburnoides: light microscopy using reagents chrome azurol S 0.5 % hematoxylin and 0.2 %; confocal microscopy with the lumogallion 10 mM, and scanning electron microscopy with attached energy dispersive spectrometer X-ray (EDS). The contents of K, Ca, Mg, P, Si, Fe and Al were determined on dry matter of vegetative organs. Samples were fixed in formalin ferrous sulphate and embedded in parafin for phenolic histolocalization and comparison with the distribution of Al, in order to investigate a possible complexation. Enzymes of the antioxidative system and the content of total soluble phenols were determined. The soils of the National Forest of Paraopeba generally have high acidity and high levels of Al. Lower values of pH (4.35 to 4.5) were found in CD. The Al contents show variations along the profile with lower levels recorded in Css Cxb. The cerrado sensu stricto had low levels of nutrients and organic matter, while CM showed higher availability of Ca and CD lower values of K and Mg. The mineral composition of the plants varied among the areas and the shoots had a higher content of Al. Individuals from Css Cxb had higher concentrations of Al in leaves and roots. The pectin-cellulosic walls and chloroplasts were the main sites of accumulation, although the relationship between Al accumulation in chloroplasts with tolerance mechanism needs to be investigated as well as the sites of metal accumulation within the organelle. The antioxidant system of R. viburnoides in different physionomies had no differences in the activity of catalase and superoxide dismutase, while peroxidase activity was lower in plants of CM in relation to plants Css LA. The differences in brightness found in the study areas may be influencing the differences in the activity of this enzyme. The phenolic compounds histolocalization not coincided with the Al organs of the plant. The highest levels of total soluble phenols evidenced in CD individuals were related to the concentration of Mn in the soil of vegetation type. The occurrence of R. viburnoides in environments with different characteristics is related to an adjustment in the device effective in physiological responses to various abiotic stresses that wild plants are subjected. The tolerance of the species at high Al concentrations in the soil relates to metal accumulation in the tissues which may also be associated with other engine that detoxification.