The fungal-specific β-glucan-binding lectin FGB1 alters cell-wall composition and suppresses glucan-triggered immunity in plants

β-glucans are well-known modulators of the immune system in mammals but little is known about β-glucan triggered immunity in planta . Here we show by isothermal titration calorimetry, circular dichroism spectroscopy and nuclear magnetic resonance spectroscopy that the FGB1 gene from the root endophyte Piriformospora indica encodes for a secreted fungal-specific β-glucan-binding lectin with dual function. This lectin has the potential to both alter fungal cell wall composition and properties, and to efficiently suppress β-glucan-triggered immunity in different plant hosts, such as Arabidopsis , barley and Nicotiana benthamiana . Our results hint at the existence of fungal effectors that deregulate innate sensing of β-glucan in plants.