CHARACTERIZATION OF CELL WALL POLYSACCHARIDES OF THE COENCOCYTIC GREEN SEAWEED BRYOPSIS PLUMOSA (BRYOPSIDACEAE, CHLOROPHYTA) FROM THE ARGENTINE COAST

M. CIANCIA, J. ALBERGHINA, P. X. ARATA, H. BENAVIDES, F. LELIAERT, H. VERBRUGGEN, J. M. ESTEVEZ.

JOURNAL OF PHYCOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2012 vol. 48 p. 326 - 335

0022-3646

Bryopsis sp. from a restricted area of the rocky shore of Mar del Plata (Argentina) on theAtlantic coast was identified as Bryopsis plumosa (Hudson) C. Agardh (Bryopsidales,Chlorophyta) based on morphological characters and rbcL and tufA DNA barcodes. In order toanalyze the cell wall polysaccharides of this seaweed, the major room temperature (B1) and 90ºC(X1) water extracts were studied. By linkage analysis and NMR spectroscopy, the structure of asulfated galactan was determined, and putative sulfated rhamnan structures and furanosidicnonsulfated arabinan structures were also found. By anion exchange chromatography of X1, afraction F4, comprising a sulfated galactan as major structure was isolated. Structural analysisshowed a linear backbone constituted by 3-linked β-D-galactose units partially sulfated on C-6and partially substituted with pyruvic acid forming an acetal linked to O-4 and O-6. This galactanhas common structural features with those of green seaweeds of the genus Codium (Bryopsidales,Chlorophyta), but some important differences were also found. This is the first report about thestructure of the water-soluble polysaccharides biosynthesized by seaweeds of the genus Bryopsis.These sulfated galactans and rhamnans were in situ localized mostly in two layers, one close tothe plasma membrane and the other close to the apoplast, leaving a middle amorphous unstainedcell wall zone. In addition, fibrillar polysaccharides, comprising (1→3)-β-D-xylans and cellulose,were obtained by treatment of the residue from the water extractions with a LiCl/DMSO solutionat high temperature. These polymers were also localized in a bilayer arrangement.