Anatomia foliar, ontogenia e histoquímica das estruturas secretoras em órgãos vegetativos de Bixa orellana L. (Bixaceae)

• Autor(a) principal: Freitas, Patrícia França de
• Data de Publicação: 2009
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2525
• topic: Bixa orellana; Estruturas secretoras; Ontogenia; Histoquímica; Bixa orellana; Secretory structures; Ontogeny; Histochemistry; CNPQ::CIENCIAS BIOLOGICAS::BOTANICA

Bixa orellana L., known as anatto, is native of South America and represent economic value, especially in food industry, as a natural reddish dye, obtained from the seed tegument. This work aimed to characterize the anatomy of B. orellana leaves, the development of secretory structures and histochemical analysis of the secretion. Samples of shoot apex, leaves, stems and roots, at different growth stages are fixed in 2,5% glutaraldeyde or in FAA50, storage in 70% ethanol and embedded in methacrylate, following the usual procedure for light microscopy. Diaphanization was carried out for venation study. For histochemical analysis, fresh samples was sectioned in a table-microtome and submitted to dyes and reagents. For micromorphological analysis, the samples were submitted to the usual procedures for scanning electron microscopy. The leaves morphoanatomical analysis shows that B. orellana follows the standard anatomical features just recorded for the Bixaceae, but shows occurrence and distribution of secretory structures with details. Peltate trichomes occur in shoot apex, but they get senescent and sparse in expanding organs. Peltate trichomes ontogeny follows the standard way as in secretory trichomes, but the secretion (terpenes and flavonoids) get stored in head cells, without the formation of a typical subcuticular space. Bixin secretory structures occur in all vegetative organs and their origin and development are pluricellular. There is a gradual fusion of cells, in what the common cell walls are degraded, forming a pluricellular structure, delimited by the remaining external cell walls, that gives rise with the formation of a central space, nuclear degradation and storage of lipidic secretion. The ducts, that yield mucilage and occur just in the shoot, show lysigenous development. Tannin cells are distributed along the vascular tissues in all vegetative organs. Ultrastructural analysis are needed to clarify some questions related to the development of B. orellana secretory structures, as the confirmation of the origin and pluricellular development of bixin secretory structures, the bixin synthesis process and the secretion compartmentalization in peltate trichomes.