Reserve Polysaccharides Other Than Starch in Higher Plants

Abstract

Reserve polysaccharides are formed by plant cells at certain physiological stages of development, usually during periods of intense photosynthetic activity, and are later “digested” to deliver carbohydrate monomers which re-enter the cells’ metabolism. They are stored — that is temporarily withdrawn from cellular metabolism — either in the solid state or, less frequently, in a dissolved or highly hydrated colloidal state. Their deposition takes place on the outside of the plasmalemma in the cell wall region, in plastids or in cell vacuoles. As far as we know, starch is the only polysaccharide formed in plastids and the plastids constitute the only cellular compartment which forms starch in higher plants.