β-glucan-triggered plant innate immunity

Fungal cell walls, essential for environmental adaptation and host colonization, have been evolutionarily selected by plants and animals as a source of Microbe-Associated Molecular Patterns (MAMPs) that upon recognition by host Pattern Recognition Receptors (PRRs) trigger immune responses conferring disease resistance. Chito-oligosaccharides (derived from chitin) are the only glycosidic structures from fungal walls well-shown to function as MAMPs in plants. Despite pioneering work and recently regained momentum, the plant-specific knowledge about the mechanisms of b-glucan perception and its role in activation of plant defence clearly lags behind the animal field. In this article, the “Plant innate Immunity and resistance to necrotrophic fungi” research group of the CBGP (UPM-INIA) demonstrates that Arabidopsis can perceive non-branched 1,3-b-glucans of various degrees of polymerization. These data support that plants, like animals, have selected as MAMPs the linear 1,3-β-D-glucans present in the walls of fungi and oomycetes. Moreover, the data published by Mélida et al. also suggest that CERK1, a PRR from Arabidopsis, functions as an immune co-receptor for linear 1,3-β-D-glucans similarly to its proposed function in the recognition of fungal chito-oligosaccharides and bacterial peptidoglycans MAMPs.