An hypothesis: The same six polysaccharides are components of the primary cell walls of all higher plants

Abstract

Publisher Summary This chapter presents an overview of primary cell walls to reach consensus on the nomenclature of primary cell wall polysaccharides. The evidences are presented supporting the hypothesis that cellulose, xyloglucan, arabinoxylan, homogalacturonan, RG-I, and RG-II are the six polysaccharides common to all primary cell walls of higher plants. In many cells, these six polysaccharides account for all or nearly all of the primary wall polysaccharides. Like the physically interacting proteins that constitute the electron transport machinery of mitochondria, the structures of the six apparently ubiquitous polysaccharides of primary cell walls have been conserved during evolution. Indeed, it is hypothesized that the common set of six structural polysaccharides of primary cell walls have been structurally conserved because they physically interact while endowing the walls with closely related mechanisms for cell enlargement, cell differentiation, and resistance to pests.