Estruturas secretoras nos órgãos vegetativos aéreos de Paullinia rubiginosa Cambess.(Sapindaceae)

• Autor(a) principal: Souza, Lucimara Amélia de
• 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/123456789/2520
• topic: Nectários; Laticíferos; Idioblastos taníferos; Tricomas secretores; Histoquímica; Ontogenia; Nectaries; Laticifers; Tanniferous idioblasts; Secretory trichomes; Histochemistry; Ontogeny; CNPQ::CIENCIAS BIOLOGICAS::BOTANICA

Paullinia belongs to the Sapindaceae family and is composed of lianas. P. rubiginosa occurs in several countries in South America, has compound leaves with five oblong leaflets acuminate at apex and dentate margins. The occurrence of secretory trichomes and the production of a latex-like secretion have been mentioned in the description of the species. In field observations we detected a small amount of secretion exuding in the teeth of the margin of young leaflets, suggesting a secretory nature for these structures. Thus, this study aims to investigate the occurrence of secretory structures in the aerial vegetative organs of P. rubiginosa, describe them and identify the major metabolite classes produced by these structures. The laticifers of P. rubiginosa are articulated and originate from the activity of the ground meristem and/or procambium. The secretory activity of laticifers is precocious, yet laticiferous cells retain their cellular division ability even during their differentiation phase. As a consequence of such divisions, the laticifer elongates through an increase in the number of cells. Laticifers have primary and pectocellulosic walls, and the secretion produced is complex, with a lipophilic character; additionally, the presence of neutral lipids, essential oil, steroids, rubber, and alkaloids has been observed. Tanniniferous idioblasts occur in all aerial organs examined. Secretory trichomes develop early and are fully differentiated and actively exuding in young leaflets and leaf primordia. Ontogenetically, trichomes initiate their development by forming a row of uniseriate cells that subsequently become biseriate, through anticlinal or asymmetric divisions in some cells of this series. The secretion produced is solely polysaccharidic and that, coupled with their precocious activity, indicate the trichomes act as colleters. Glands present on the margins of leaflets develop very precociously, retaining their secretory aspect even in mature leaves. Glands are vascularized by xylem and phloem, and the latter is enveloped by a cellular sheath with phenolic and laticiferous compounds. The secretory portion of the structure reacted positively to polysaccharides, and the presence of glucose in the released secretion was established. Therefore, these structures correspond to extrafloral nectaries (EFNs). The presence of EFNs and the occurrence of laticifers in P. rubiginosa are promising results that have to be taken into account in future studies on taxonomy and phylogeny at the genus and family levels, and even at the order Sapindales.