An integrated fruit model toolkit: combining fruit biophysical processes with central carbon metabolism

Fruits, consumed freshly or after processing, play an important role in the human diet. Yield and fruit quality are the two most important criteria for fruit production. Yield of fleshy fruits is largely determined by water, while their quality is mainly determined by biochemical composition. How do fruit growth and metabolism interact remains largely unknown? Process-based models can simulate the biophysical water transport processes for fruit growth, without detailed incorporation of metabolic processes. The kinetic models of carbohydrate metabolism allow the calculation of metabolic fluxes, thus metabolite concentrations. Our objective is to develop an integrated model toolkit that links fruit metabolism with biophysical growth, in order to assess the interactions between fruit biophysical properties and fruit metabolisms in different fruit species. We have firstly constructed and tested an integrative model in tomato. The model runs in a dynamic mode and bridges the gap between biophysical processes and metabolic networks. It was able to well reproduce the developmental profiles of fruit fresh and dry weight, the concentration of the main soluble sugars (glucose, fructose, and sucrose), and the content of starch and cell wall in tomato fruit. Global sensitivity analysis was conducted on parameters related to fruit biophysical properties and enzyme properties. Preliminary results showed that biophysical property parameters can exert important influence on central carbon metabolism, while enzyme kinetic parameters show less impact on fruit growth. Further application of the model to other fruit species will allow identifying conserved and/or species-specific interaction modes between growth and metabolism. Ultimately, the integrated model would provide a helpful toolkit to deal with the complexity of the interplay between fruit development, metabolism and environment, leading to new possibilities regarding targeted manipulation and breeding for fruit yield and quality