S17 - Session O3 - A virtual fruit model to simulate water deficit effects on water and solutes accumulation in the fruit and the consequences on fruit quality.

Authors: Dario Constantinescu *, Michel Génard, Gilles Vercambre, Nadia Bertin

Fruit size and solute composition are quality traits and are mainly determined by soluble sugars, acids, and minerals concentrations that depend on water and solute translocation and metabolism. Water and sugar translocation depends on transport mechanisms that take place in the vascular system connecting the plant and the fruit. These transports are driven by the fruit osmotic pressure, which is determined by the concentrations of solutes in the fruit pulp. Nevertheless, this concentration determines the fruit osmotic potential itself. Therefore, there is strong feedback between the solutes and water translocation, metabolism and fruit growth. Water deficit leads to changes in the water status of plants and therefore affects fruit growth. Understanding links between fruit growth processes and the plant growing conditions can be important to improve agricultural techniques and fruit quality. In this work, we show how we can describe such a complex system through a virtual fruit model, i.e. a process-based model composed of sub-modules that describe fruit growth and sugar and acid metabolism by using biophysical relationships. The model well-fitted measurements of tomato fruit size, and solutes content and concentrations made on three cohorts of two commercial varieties. We simulated the model on two scenarios of water deficit and we explored how the biophysical processes involved lead to changes in fruit growth with a focus on the role of sugar and acid accumulation and metabolism. The simulation results suggested that acid concentrations variations might affect fruit growth and that water deficit conditions might indirectly affect acid and sugar metabolism and then fruit growth and composition. The presented virtual fruit model is a promising tool to untangle the complex processes that involve fruit growth and to simulate environmental conditions for predicting fruit growth processes response and their effect on fruit size and taste.