Reserve Carbohydrates of Algae, Fungi, and Lichens

Abstract

In higher land plants, there is a clear-cut distinction between starch or certain fructans which function as the major reserve carbohydrate, and structural polysaccharides such as cellulose, the hemicelluloses, and the pectic substances. Moreover, there is normally little difficulty in obtaining adequate amounts of plant tissue from which the various polysaccharides can be isolated and then characterized. By contrast, in the lower plant kingdom, several different types of polysaccharide may occur within the same plant tissue, and while a structural function for some polysaccharides is obvious, the functions of others (which may be water-soluble) are not always evident. With some algae, fungi, and lichens, some polysaccharides are believed to have a reserve function, although metabolic evidence is not available, and their inclusion or exclusion from this review is based on somewhat tenuous experimental results.