Fruit Integrative Modelling – ERASYsBIO (ANR-09-SYSB-0003)

Commercial fruit production is under significant pressure from environmental stresses, but also by changes in the consumer’s demand for taste and nutritional value. One key goal of fruit biology is therefore to understand the factors that influence metabolite levels. Both genetic and environmental factors have a strong and multifaceted influence on fruit quality. They act and interact in such a complex way that it is extremely difficult to study their effects experimentally. To circumvent such difficulty, we will build a virtual tomato fruit that enables the prediction of metabolite levels given genetic and environmental inputs, by an iterative process between laboratories which combine expertise in fruit biology, ecophysiology, theoretical and experimental biochemistry, and biotechnology. There are three major aims:(1) To build a kinetic model encompassing the routes carbon takes, once imported into the fruit cells from the source organs of the mother plant. The model will include subcellular compartmentation. To parameterize the model, data for enzyme and transporter properties and metabolite levels will be measured in fruits harvested at different developmental stages and grown under contrasted environments.(2) To integrate the kinetic model with a phenomenological model predicting sugar and organic acid contents as functions of time, light intensity, temperature and water availability. Sub-models describing carbon and water transfer within the plant, fruit growth, sugar and organic acid accumulation will be implemented and integrated with the kinetic model. This “multi-scale” integration will then be used to run virtual experiments.(3) To obtain large-scale experimental measures of the consequences of altered environmental conditions. Such studies will allow validation and iterative optimization of the model. As a first application of the combined model, environmental scenarios leading to metabolic phenotypes will be searched in silico for existing transgenic plants with altered enzyme activities, and validated