Mauritia flexuosa palms inhabit wetland environments in the dry, seasonal Brazilian savanna (Cerrado) and produce mucilaginous secretions in the stem and petiole that have a medicinal value. The present study sought to characterize the chemical natures of those secretions and to describe the anatomical structures involved in their synthesis. Chemical analyzes of the secretions, anatomical, histochemical analyses, and electron microscopy studies were performed on the roots, stipes, petioles, and leaf blades. Stipe and petiole secretions are similar, and rich in cell wall polysaccharides and pectic compounds such as rhamnose, arabinose, xylose, mannose, galactose, and glucose, which are hydrophilic largely due to their hydroxyl and carboxylate groups. Mucilaginous secretions accumulate in the lumens of vessel elements and sclerenchyma fibers of the root, stipe, petiole, and foliar veins; their synthesis involves cell wall loosening and the activities of dictyosomes. The outer faces of the cell walls of the parenchyma tissue in the mesophyll expand to form pockets that rupture and release pectocellulose substances into the intercellular spaces. The presence of mucilage in the xylem, extending from the roots to the leaf veins and continuous with the leaf apoplast, and sub-stomatal chambers suggest a strategy for plant water economy.

In ruminant diets, soluble sugar is an important factor in the digestive process. The objective of this study was to evaluate the effects of the source and dose of soluble sugars, under controlled pH conditions, on the in vitro digestibility of DM, fibre fractions (NDF and ADF) and cell wall neutral monosaccharides of corn silage. Silage was collected from several points in a silage mass from a bunker silo, oven-dried at 55°C and ground through a 1-mm screen. Sub-samples were combined with sugars to compose the treatments, in a 5 × 5 factorial arrangement, as a combination of five soluble sugar sources (glucose, fructose, arabinose, xylose and sucrose) and five sugar doses (0, 100, 200, 300 and 400 g/kg sugar in DM corn silage), respecting the following proportions of sugar : corn silage, 0 : 100, 10 : 90, 20 : 80, 30 : 70, 40 : 60 represented by the sugar doses, respectively. An in vitro test was performed to determine the true digestibility (D) of the chemical entities (DM, NDF and ADF) and cell wall monosaccharides (glucose = gluc, arabinose = arab and xylose = xyl). During the first 12 h of incubation, the pH was maintained above 6.0 by the addition of 2.5 N NaOH. The concentrations of neutral monosaccharides (arabinose, xylose and glucose) were determined by GLC. The soluble sugars decreased the digestibility of corn silage followed by pH reduction, especially at doses higher than 200 g/kg sugar. Overall, xylose, followed by sucrose, fructose and arabinose, had greater impacts on DM digestibility, whereas fibre digestibility was impaired by sucrose at all doses. Xylose and fructose had greater impacts on NDF digestibility at 300 and 400 g/kg sugar. Although xylose impaired the Dgluc in the cell wall in all doses. All doses of glucose improved the Dgluc and Dxyl in the cell wall.