HISTOLOGICAL AND CHEMICAL CHARACTERIZATION OF MYRSINE LAETEVIRENS SEED

Histological and chemical features in seeds of Myrsine laetevirens are described. Seed is endospermous and the endosperm consists of several layers of thick cell walls that store mainly xyloglucans. Next to the embryo, the endosperm cell walls are rich in pectins. In the endosper m, proteins are stored in typical protein bodies. In the embryo, vacuo les with small deposits of protein inside were distinguished. Globoids , found in the protein bodies of the endosperm, are absent in the embr yo tissues. Energy-dispersive x-ray analysis of globoid revealed P, Mg , K, and Ca as the main nutrient minerals. Lipid vesicles are present in embryo and endosperm; in the embryo they are found mainly along the periphery of the plasmalemma. Determination of neutral sugars was per formed after acid hydrolysis. Sugars were identified by high-performan ce anion exchange chromatography (Dionex). Arabinose, xylose, glucose, and galactose are the main monosaccharides, but the ratio differs in endosperm and embryo tissues. Uronic acids were determined by a colori metric reaction. Analysis of fatty acids by capillary gas-liquid chrom atography revealed the presence of C16:0, C18:0, C18:1, and C:18:2 fat ty acids in embryo and endosperm. In the latter, traces of C12:0 also were detected. Soluble proteins were analyzed by polyacrylamide gel el ectrophoresis, which showed a different profile in both tissues. Few b ands are glycosylated. This investigation was undertaken in order to i nitiate studies of the seed in the genus Myrsine. Similar studies in o ther genera of Myrsinaceae have not been reported, precluding a taxono mical comparison.