A kinetic model of sugar metabolism in peach fruit reveals a functional hypothesis of markedly low fructose-to-glucose ratio phenotype

International audienceThe concentrations of sugars in fruit vary with fruit development, environment, and genotype.In general, there were weak correlations between the variations in sugar concentrations andthe activities of enzymes directly related with the synthesis or degradation of sugars. Thisfinding suggests that the relationships between enzyme activities and metabolites are oftennon-linear and are difficult to assess. To simulate the concentrations of sucrose, glucose,fructose and sorbitol during the development of peach fruits, a kinetic model of sugarmetabolism was developed by taking advantage of recent profiling data. Cellcompartmentation (cytosol and vacuole) was described explicitly, and data-driven enzymeactivities were used to parameterize equations. The model correctly accounts for both annualand genotypic variations, which were observed in ten genotypes derived from an interspecificcross. They provided important information on mechanisms underlying the specification ofphenotypic differences. In particular,the model supports the hypothesis that a difference infructokinase affinity could be responsible for a low fructose-to-glucose ratio phenotype,which was observed in the studied population