β-Glucanases in Higher Plants: Localization, Potential Functions, and Regulation

Abstract

Polysaccharides with d-glucopyranose units joined in glucosidic linkages are the most abundant organic substances on earth. The major β-linked glucan polysaccharides are β1,4-glucan (cellulose) and β1,3-glucans (e.g., curdlan, callose). Other β-glucans have a backbone of β-1,3-linked glucose units associated with variable and low proportions of internal β1,4- or β1,6-linkages (e.g., pachyman, laminarin) or associated in a regular pattern with relatively high proportions of β1,4-linkages (mixed-linkage glucans).