Fig. 3

Structural model of the plant cell wall that illustrated a putative model of a plant secondary cell wall. The model shows several cellulose synthase complexes (CSCs) embedded in the plasma membrane depositing cellulose chains into the apoplast as microfibrillar bundles. Hemicelluloses such as glucuronoxylan associate non-covalently to the surfaces of the cellulose microfibrils, while lignification occurs into the cellular voids remaining as the cells enter into programmed cell death. A schematic chemical makeup and linkage of several major and minor cell wall polymers are also shown. Yellow hexagon and blue circle, glucose; dark orange star, xylose; blue–white diamond, glucuronic acid; orange circle, galactose; green triangle, rhamnose; green circle, mannose; orange–white diamond, galacturonic acid; green star, arabinose; blue pentagon, apiose; red triangle, fucose; dark red circle, O-acetyl; teal circle, O-methyl