Mobilização de reservas nas sementes de Moringa oleifera Lam. (MORINGACEAE) durante a germinação

Abstract

Moringa oleifera Lam. (Moringaceae) is native to India, been widely cultivated in the tropics and subtropics. In Brazil, it is widely found in the Northeast, due to its resistance to droughts, Adaptation to climatic conditions and arid soils. This work investigates the mobilization of reserves of M. oleifera seeds during germination. The seeds were germinated and withdrawn in accordance with the times: T0 (0h), T1 (24 hours) and T2 (48 hours) after soaking and size radicle T3 (protrusion) to T8 (2.1 cm onwards). The seeds were transversally sliced, fixed in glutaraldehyde 1% and paraformaldehyde 4% in 0,1M sodium phosphate buffer, dehydrated in an ethanolic crescent series, included in Leica Historesin and sliced in semi-automatic microtome. The sections were submitted to the following colors: Toluidine Blue (AT), for detection of anionic radicals; Xylidine ponceau (XP) for cationic radicals; reaction of periodic acid-Schiff (PAS) for neutral polysaccharides and Sudan IV, for lipids. For the chemical determinations 0.2g of plant material were used, which was defatted with hexane and the supernatant was transferred to containers of known mass. After evaporation of the hexane, the lipids content was determined by weight difference. Proteins and carbohydrates were determined by Bradfort and anthrone methods, respectively. After three days, the radicle protrusion occurred and the development of photosynthetic stem in five or six days. The colorations with AT and PAS evidenced the cotyledon‟s cell wall due to the presence of pectin and neutral polysaccharides, respectively. The staining in XP noted dissolved protein in the cytoplasm between the lipid globules. There was a reduction from T0 to T8 of 60% in protein levels. Through Sudan IV was observed the mobilization of lipids, corroborating with chemical determination, with reduction from T0 to T8 of 30,44%. The results show that the main reserve of moringa seeds are lipids then carbohydrates, with increase from T0 to T8 of 44%. The tenors of lipids reduce during seed germination (from T0 to T8), been mobilized to the embryo‟s growth. These oils present potentialities to several applications, considering important the study of those reserves‟ characteristics in moringa‟s seeds.