Plant Cell Walls

Abstract Common to all plant species, the cell wall is the tough outer coat that protects the plant cell. The cell wall is mostly carbohydrate‐based, comprising three major classes of polysaccharides: cellulose, hemicellulose and pectin. There are also important structural proteins as well as phenolic and aliphatic polymers. The cell wall provides mechanical strength to the plant body, allowing upright growth and structure formation, and also plays important roles in cellular processes such as cell expansion, tissue differentiation, intercellular communication, water movement and defence responses against pests or pathogens. Cell walls may even be involved in signal sensing during pattern formation in plant development. Key Concepts The cell wall is the outermost layer of the plant cell. The cell wall consists essentially of three major types of carbohydrates – cellulose, hemicellulose and pectins – and proteins. Some specialised cell wall types, for example woody cell walls also contain phenolic and aliphatic polymers in addition to carbohydrate polymers. The cell wall is a dynamic structure whose composition changes during cell, tissue and plant development and in response to various stresses. The cell wall provides mechanical strength to the plant body. The cell wall plays important roles in processes such as cell expansion, tissue differentiation, intercellular communication, water movement and defence responses against pests or pathogens.