Células epidérmicas mucilaginosas facilitam a manutenção hídrica foliar em espécies do semiárido?

Abstract

In environments with severe water deficit, plants have mechanisms that allow the absorption of water and maintenance of water status. Mucilage secretion by plants has been reported as a way to reduce transpiration and water loss, to maintain moisture in tissues and water potential and as a carbohydrate reserve. However, experimental evidence supporting the role of mucilages in these environments is scarce. To survey if the occurrence of mucilaginous epidermal cells increases leaf water potential, we evaluated the water uptake, water potential and gas exchange of leaves of leguminous species with and without mucilage in the epidermis. Our results indicated that mucilage present in epidermal cells is not always directly involved with water absorption. Tests with the Lucifer Yellow apoplastic tracer (LY) showed that there was foliar water absorption, but there was no retention of LY in mucilaginous cells. Though, the species with mucilage absorbed water through the epidermis and the leaf water potential was less negative than in L. ferrea, indicating that these polysaccharides in the epidermis help in the water economy of the plant.