Borreria verticillata (Rubiaceae): Caracterização Nutricional e Respostas Morfofisiológicas ao Arsênio

• Autor(a) principal: Silva, Samara Arcanjo e
• 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/123456789/2560
• topic: Borreria verticillata - Anatomia; Borreria verticillata - Fisiologia; Borreria verticillata - Populações; Arsênio; Poluição; Plantas - Nutrição; Verticillata Borreria - Anatomy; Verticillata Borreria - Physiology; Verticillata Borreria - Populations; Arsenic; Pollution; Plants - Nutrition; CNPQ::CIENCIAS BIOLOGICAS::BOTANICA

Arsenic (As) is an element toxic to living beings which is released on the environment by natural and anthropic sources. Phytoremediation the utilization of plants on the recovery of contaminated environments requires selecting species that are tolerant to the pollutant. Borreria verticillata is found in environments with high concentrations of As in the soil, for example Morro do Galo (municipality of Nova Lima/MG). Studies developed in Hoagland nutrient solution found higher tolerance on plants from the Morro do Galo than plants from the site without metalloid (Mata do Paraíso, municipality of Viçosa/MG). Choosing the nutrient solution is an important aspect due to the competition between arsenate and phosphate for the same membrane transporters. This work aimed to study the development of plants of B. verticillata in Hoagland and Clark nutrient solutions, in order to determine the formulation more indicated for studies of their morphophysiological responses to As, with the objective of elucidating tolerance mechanisms present on populations acclimatized and non-acclimatized to As. Plants of B. verticillata of populations from Morro do Galo (MG) and Mata do Paraíso (MP) were cultivated in Hoagland and Clark solutions at 1⁄2 strength during 40 days, and growth and nutritional efficiency were determined. Plants showed more homogenous responses when cultivated in Clark solution. When cultivated in Hoagland solution, plants from MP were superior regarding nutrient accumulation and growth, and similar to plants from MG regarding nutritional efficiency. As such, Clark solution was more indicated for studying the tolerance of the species to As, due to the similar response of the two populations and to the lower phosphorous concentration. Therefore, plants of B. verticillata from MG and MP were cultivated in Clark solution at 1⁄2 strength containing 0.0 and 66.0 μM of As for 4 days, for investigation of the mechanisms that provide differential tolerance to As on the two populations. For this, accumulation and distribution of As and macronutrients, as well as morphophysiological responses of plants to this pollutant, were studied. The higher accumulation of As on roots was responsible for the occurrence of more severe damage on this organ, however, symptoms of toxicity were also observed on shoots of both populations. The presence of As in the nutrient solution promoted alterations on the nutritional characteristics of plants from MG, such as increase on the accumulation of calcium on roots, reduction on the translocation factor of phosphorous, calcium and sulfur, as well as increase on the production of crystalliferous and phenolic idioblasts on roots, increment on the activity of superoxide dismutase and synthesis of thiolated compounds on leaves. Plants from MP, on the other hand, exhibited increment on the number of phenolic idioblasts on roots and increase on the activity of polyphenol oxidase on leaves. The As detoxification strategies presented by plants from MG provided this population with higher tolerance to the metalloid, suggesting possible utilization on revegetation of contaminated environments.