Emerging Roles of β-Glucanases in Plant Development and Adaptative Responses

Plant beta-glucanases are enzymes involved in the synthesis, remodelling and turnover of cell wall components during multiple physiological processes. Based on the type of the glycoside bond they cleave, plant beta-glucanases have been grouped into three categories: (i) beta-1,4-glucanases degrade cellulose and other polysaccharides containing 1,4-glycosidic bonds to remodel and disassemble the wall during cell growth. (ii) beta-1,3-glucanases are responsible for the mobilization of callose, governing the symplastic trafficking through plasmodesmata. (iii) beta-1,3-1,4-glucanases degrade mixed linkage glucan, a transient wall polysaccharide found in cereals, which is broken down to obtain energy during rapid seedling growth. In addition to their roles in the turnover of self-glucan structures, plant beta-glucanases are crucial in regulating the outcome in symbiotic and hostile plant-microbe interactions by degrading non-self glucan structures. Plants use these enzymes to hydrolyse beta-glucans found in the walls of microbes, not only by contributing to a local antimicrobial defence barrier, but also by generating signalling glucans triggering the activation of global responses. As a counterpart, microbes developed strategies to hijack plant beta-glucanases to their advantage to successfully colonize plant tissues. This review outlines our current understanding on plant beta-glucanases, with a particular focus on the latest advances on their roles in adaptative responses.

Automated summary

Plant beta-glucanases play crucial roles in the synthesis, remodelling and turnover of cell wall components. They cleave different types of glycoside bonds to remodel and disassemble the cell wall, and are involved in regulating symbiotic and hostile plant-microbe interactions.