Process-based simulation models and plant phenotyping

Plant phenotyping is difficult due to the complexity of the plant system and its sensitivity to developmental stages, environmental conditions and interactions between these and the genotype. Process-based simulation models can combine different biological functional hypotheses on responses of plant processes to environmental fluctuations. They then allow a virtual representation of plant functioning and can be useful tools to phenotype plants in terms of ecophysiological processes. The Virtual Fruit model (VF) developed by adapting and connecting existing models describing fruit growth, transpiration and respiration, sugar and acid accumulation and ethylene production was used to illustrate the approach. It permitted to compare and contrast the performances of a virtual wild-type plant and a virtual mutant, and then analyse the impact of a single mutation on different processes. The tested virtual mutations corresponded to 1) an increase by a factor 5 of the mobile fraction of plant reserves that can be mobilised to sustain carbon supply to the fruit or 2) a decrease by 70% the fruit's requirement for carbon. The mutation on fruit's requirement for carbon had large effects on several physiological processes (growth, respiration, metabolism and maturation) and quality traits (size, sucrose and citric acid concentration). In contrast, the mutation on reserve mobilization had only a weak effect on fruit growth and acidity. Such a virtual profiling approach can open new avenues for exploring in silico the impact of genetic variations.