Morfoanatomia dos órgãos vegetativos de Mandevilla atroviolacea (Stadelm.) Woodson (Apocynaceae, Apocynoideae) em um afloramento rochoso no Parque Estadual da Serra do Brigadeiro MG

• Ano de defesa: 2007
• Autor(a) principal: Lopes, Karina Lucas Barbosa
• Orientador(a): Meira, Renata Maria Strozi Alves
• Banca de defesa: Vale, Fernando Henrique Aguiar , Silva, Luzimar Campos da
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Botânica
• Departamento: Botânica estrutural; Ecologia e Sistemática
• País: BR
• Palavras-chave em Português: Mandevilla; Sistema subterrâneo; Laticíferos
• Palavras-chave em Inglês: Mandevilla; Underground system; Laticiferous
• Área do conhecimento CNPq: CNPQ::CIENCIAS BIOLOGICAS::BOTANICA::MORFOLOGIA VEGETAL::ANATOMIA VEGETAL
• Link de acesso: http://locus.ufv.br/handle/123456789/2578

Mandevilla atroviolacea (Apocynaceae, Apocynoideae) is a wine species characterized by the presence of latex in the vegetative organs, stunning flowers and well-developed underground system. In the Serra do Brigadeiro State Park- MG (PESB), M. atroviolacea occurs in an isolated or forming population of individuals on rock outcrops at 1400m of altitude. Plants occurring in these environments usually show adaptations to water and substratum shortage. The objective of this work was the morpho-anatomical characterization of vegetative organs of M. atroviolacea ocurring in an altitude field of the PESB, emphasizing the characterization of the laticiferous and underground systems, in order to identify structures that can assist the interpretation of adaptative strategies, as well as those of taxonomic value. Samples of stem and root apexes, leaves, stems and tuberous roots, as well as parts of hypocotyls and tuberous organs from young and adult plants were collected from a rock outcrop in the PESB. These samples were then fixed with 2% glutaraldeyde in 0.1 M Sorenson s sodium phosphate buffer, pH 7, dehydrated with an ethanol series and embedded in historesin. Sections (7- 10mm thick) were made with a rotative microtome, stained with Toluidine Blue in acid pH and slides were mounted in synthetic resin. Histochemical tests were carried out in samples of leaves, stems and roots, sectioned in a table microtome and the slides were mounted in 50% glycerin. The underground system of M. atroviolacea corresponds to a xylopodium in the proximal portion with self- rafting of shoots and high shoot-forming capacity, and in the distal portion a tuberous organ of stem origin, associated with tuberous lateral roots. In these roots, there is proliferation of cortical parenchyma cells and secondary phloem, forming a tissue related with storage of water (succulent roots) and reserve substances, mainly starch. M. atroviolacea has articulated anastomosing laticifers originated from the activity of the primary meristem and/or the procambium that show secretory activity early in their formation in the meristematic region. In tuberous roots, the laticifers are originated from the activity of the cambium and/or phellogen and dedifferentiation of cortex parenchyma cells. The laticifers present exclusively primary pectocellulose walls thicker than the adjacent cell walls. The laticifer secretion contains an emulsion of lipophilic substances, rich in neutral lipids, oil-resins and rubber. The high shoot- forming potential and storage of water and reserve substances of the M. atroviolacea underground system, as well as the presence of latex in vegetative organs conferring protection against pathogens and herbivores, represent important strategies for the species survival in these adverse conditions.