ABSTRACT
Most photosynthetic organisms share one feature, which is the presence of polysaccharide-rich cell walls that play fundamental roles in physiology and biomechanical properties. Cell walls are highly dynamic and their composition varies depending on cell type, tissue type, and developmental stage. Further variation is seen in response to environmental stresses. The likelihood that cell wall components, and the overall wall composition of a plant or alga, have been shaped and optimised in different lineages is perhaps therefore intuitive. However, since cell wall components are necessarily highly interconnected and interdependent in order to maintain cell wall integrity and to carry out their many roles, the freedom with which individual wall components can be modified is a more open question. This chapter explores the evolutionary mechanisms, and selection pressures, that may have resulted in the taxonomic variation present in the cell wall compositions of extant plants and algae.
