Fruit development, from its early stages, is the result of a complex network of interacting processes, at different scales. These include cell division, cell expansion, the main determinants of final fruit size, but also nutrients transport from the plant and exchanges with the environment. In spite of their known importance, the functional links between cell division, expansion remain unclear and the effect of environment on individual processes is not well quantified.

Here we present an integrated model of tomato, explicitly accounting for cell proliferation and expansion processes, and use it to investigate the impact of water deficit and carbon limitation on nutrients fluxes and fruit growth, in both dry and fresh mass.

Variability in fruit response is analyzed at two different scales: among trusses, at the plant level and within the cells population, at the fruit scale. Results show the effect of stress on individual cells strongly depends on their age, size and uptake capabilities and that the timing of stress application, together with the fruit position on the plant, is crucial to determine the final phenotypic outcome. An important prediction of the model is the importance of symplasmic transport of carbon in early stage of fruit development, as a catalyst of cells and fruit growth.

In the future, the addition of DNA endoreduplication to the model and the description of the cell cycle adjustments to environmental conditions will help to refine model predictions, shedding light on the complex control of growth plasticity.