A gnotobiotic growth assay for Arabidopsis root microbiota reconstitution under iron limitation.

We present a gnotobiotic system for microbiota reconstitution on Arabidopsis thaliana under contrasting iron availability. This system induces iron starvation in plants by providing an unavailable form, mimicking conditions in alkaline soils. Inoculation of taxonomically diverse bacteria reconstitutes plants with a synthetic microbiota, allowing observation of nutrient-dependent interactions with commensals. Experimental optimization, including media composition and preparation of seedlings and bacteria, is discussed. This system provides a framework that can be adapted to study plant-microbiota interactions in further nutritional contexts. For complete details on the use and execution of this protocol, please refer to Harbort et al. (2020).