Fucoidans of brown algae: Biosynthesis, localization, and physiological role in thallus

Abstract

The issues of the structure and biosynthesis of fucose-containing sulfated polysaccharides are considered in this review; the data on the localization of fucoidans in tissues and their significance for algae are provided. Fucoidans participate in the building of cell walls and the support of their structure, as well as in extrusion of spores and gametes from reproductive organs. Due to the sulfated groups, these polysaccharides can bind cations (mainly K+, Na+, Ca2+, Mg2+) and participate in ion exchange with the environment, which facilitates adaptation of algae to water salinity fluctuations and to the toxic effects of heavy metals. Fucoidans play a substantial role in morphogenesis of zygotes of fucoid algae, as they participate in establishing the cell polarity and fixing the cell-division axis, thus determining the direction for the development of the rhizoidal and apical poles of young thalli.