β-Glucan Synthesis Gene Family in Crops: Advances in Classification, Function, and Regulation

β-glucan is an important component of crop cell walls, and its chemical structure is closely related to its physiological function. Among them, (1,3;1,4)-β-glucan (mixed-linkage β-glucan, MLGs) is a unique type of β-glucan in graminaceous crops. In recent years, the identification and functional analysis of the β-glucan synthesis gene family have provided key molecular targets for quality improvement of crops. This review systematically examines the classification, structure, and function of the β-glucan synthetic gene family, focusing on the regulatory network. This will lay a theoretical foundation for the further improvement of the β-glucan content in crops.