A new 3D shoot-root model for simulating rhizodeposition processes in the context of whole plant growth

International audience; Rhizodeposition, i.e. the release of any organic material by roots, has been suggested to represent a major input of carbon in soils and to shape biological activity in the rhizosphere. Various rhizodeposits can be emitted by roots, e.g. soluble exudates, secreted mucilage, sloughed cells, or volatile organic compounds. Despite their short lifetime, some of these products have been shown to favor plant growth by increasing water or nutrient uptake, by promoting plant resistance, or by acting as signals. Rhizodeposition also represents a significant share of plant’s carbon budget and may affect plant growth in this way. So far, no computational model has integrated the variety of rhizodeposition processes into plant functioning. Our goal is to develop such a model in order to investigate in a more mechanistic way the effects of contrasted plant traits, crop management or climate change on plant growth and soil carbon sequestration. As an important step in this direction, we focus here on the integration of the carbon fluxes related to rhizodeposition processes into a functional-structural plant model. After summarizing the current knowledge on the mechanisms and carbon-costs associated to rhizodeposition, we will present a 3D shoot-root model implemented in the OpenAlea platform, which integrates a new rhizodeposition model, a root architecture model (ArchiSimple) and a model of C and N metabolism in the whole plant (CN-Wheat). The possibilities opened up by this integrative model will be illustrated by simulations of net sugar exudation fluxes distributed across a dynamic, 3D wheat root system interacting with soil.