Anatomia, histoquímica e composição dos ácidos graxos de sementes de Pentaclethra macroloba (willd.) kuntze (caesalpinioideae - leguminosae).

Abstract

Pentaclethra macroloba (Willd.) Kuntze is an oilseed, popularly known as pracaxi. It can be used for ecological purposes in the conservation and recovery of degraded areas, as it is a nitrogen-fixing species in the soil. The oil from its seeds has aroused great interest in the industry, especially in cosmetics and pharmaceuticals, which led to the objective of this study, that is, to describe the anatomical and histochemical aspects and the composition of fatty acids present in the seeds of Pentaclethra macroloba. The fruits were collected from matrices located in the cities of Belém, Marituba and São Domingos do Capim, Pará. The seeds were sectioned transversally and longitudinally to the embryonic axis and fixed in FAA 50, FNT and SFF. For the anatomical study, the seeds were submitted to the usual techniques of light microscopy and scanning electron microscopy. Histochemical tests were performed on samples sectioned freehand and embedded in paraplast. In cross section, the tegument is formed by three strata, uniseriate exotesta covered by cuticle, multiseriate mesotesta formed by horizontally elongated cells and uniseriate endotesta. Cotyledons are formed by parenchyma cells with the presence of secretory structures, such as cavities and idioblasts and collateral vascular bundles. The embryo's protoderm is uniseriate, formed by rectangular cells and covered by a cuticle. The fatty acids with the highest concentration are oleic, behenic, lignoceric and linoleic. The seeds of Pentaclethra macroloba have important anatomical characteristics for circumscription of the species in caesalpinioideae, and its oil is rich in unsaturated and saturated fatty acids.