ß-Glucan-binding proteins are key modulators of immunity and symbiosis in mutualistic plant-microbe interactions.

ABSTRACT

In order to discriminate between detrimental, commensal, and beneficial microbes, plants rely on polysaccharides such as ß-glucans, which are integral components of microbial and plant cell walls. The conversion of cell wall-associated ß-glucan polymers into a specific outcome that affects plant-microbe interactions is mediated by hydrolytic and non-hydrolytic ß-glucan-binding proteins. These proteins play crucial roles during microbial colonization they influence the composition and resilience of host and microbial cell walls, regulate the homeostasis of apoplastic concentrations of ß-glucan oligomers, and mediate ß-glucan perception and signaling. This review outlines the dual roles of ß-glucans and their binding proteins in plant immunity and symbiosis, highlighting recent discoveries on the role of ß-glucan-binding proteins as modulators of immunity and as symbiosis receptors involved in the fine-tuning of microbial accommodation.