STRUCTURE AND BIOGENESIS OF THE CELL-WALLS OF GRASSES

The chemical structures of the primary cell walls of the grasses and t heir progenitors differ from those of all other flowering plant specie s. They vary in the complex glycans that interlace and cross-link the cellulose microfibrils to form a strong framework, in the nature of th e gel matrix surrounding this framework, and in the types of aromatic substances and structural proteins that covalently cross-link the prim ary and secondary walls and lock cells into shape. This review focuses on the chemistry of the unique polysaccharides, aromatic substances, and proteins of the grasses and how these structural elements are synt hesized and assembled into dynamic and functional cell walls. Despite wide differences in wall composition, the developmental physiology of grasses is similar to that of all flowering plants. Grass cells respon d similarly to environmental cues and growth regulators, exhibit the s ame alterations in physical properties of the wall to allow cell growt h, and possess similar patterns of wall biogenesis during the developm ent of specific cell and tissue types. Possible unifying mechanisms of growth are suggested to explain how grasses perform the same wall fun ctions as other plants but with different constituents and architectur e.