The new view of the primary cell wall

The plant cell wall is essential to almost every aspect of plant life. The cell wall is a dynamic and highly ordered complex of polysaccharides, structural proteins and phenolics. The introduction of new techniques in the study of cell-wall architecture, namely the availability of antibodies to cell wall components, new methods in electron microscopy, application of physico-chemical techniques like FTIR and NMR as well as refined biochemical analyses have substantially changed our conception of the cell wall. The extracellular matrix is no longer understood as a static, mainly covalently cross-linked macromolecular structure but as a flexible, developmentally regulated network that is largely based on non-covalent interactions. Three principally independent but interacting networks that form local microdomains can be distinguished: The cellulose-microfibril-xyloglucan network, the network of pectins and the network of structural cell wall proteins. This review summarizes the current ideas about the architecture and biochemical composition of primary cell walls.