STRUCTURE OF THE CELL WALLS OF MARINE ALGAE AND ECOPHYSIOLOGICAL FUNCTIONS OF THE MATRIX POLYSACCHARIDES

Abstract

In this review we describe the chemical composition and the three-dimensional organization of the skeletal and matrix polysaccharides of the cell walls of marine algae. Emphasis is placed on the mechanisms of self-association of matrix polysaccharides and the influence of life history on wall chemistry. In an attempt to draw a comprehensive picture of the organization of the wall at the cellular level, we analyse the anatomical and biochemical relationships between the various wall polymers. Several features emerge from the literature reviewed: cell walls of marine algae are unusual in the prevalence of acidic polysaccharides over the neutral polymers and by an extensive intercellular matrix; all marine algae contain sulphated wall polysaccharides, whereas such polymers are not found in land plants; the proportion of highly acidic polysaccharides is greater in the outer regions of the wall and in the outer cellular layers of the thallus. In view of this and of the characteristics of the marine environment, the physiological significance of the matrix in hydration, mechanical, and ionic regulation are discussed.