Remarkable Reproducibility of Enzyme Activity Profiles in Tomato Fruits Grown under Contrasting Environments Provides a Roadmap for Studies of Fruit Metabolism    

Abstract

To assess the influence of the environment on fruit metabolism, tomato (Solanum lycopersicum 'Moneymaker') plants were grown under contrasting conditions (optimal for commercial, water limited, or shaded production) and locations. Samples were harvested at nine stages of development, and 36 enzyme activities of central metabolism were measured as well as protein, starch, and major metabolites, such as hexoses, sucrose, organic acids, and amino acids. The most remarkable result was the high reproducibility of enzyme activities throughout development, irrespective of conditions or location. Hierarchical clustering of enzyme activities also revealed tight relationships between metabolic pathways and phases of development. Thus, cell division was characterized by high activities of fructokinase, glucokinase, pyruvate kinase, and tricarboxylic acid cycle enzymes, indicating ATP production as a priority, whereas cell expansion was characterized by enzymes involved in the lower part of glycolysis, suggesting a metabolic reprogramming to anaplerosis. As expected, enzymes involved in the accumulation of sugars, citrate, and glutamate were strongly increased during ripening. However, a group of enzymes involved in ATP production, which is probably fueled by starch degradation, was also increased. Metabolites levels seemed more sensitive than enzymes to the environment, although such differences tended to decrease at ripening. The integration of enzyme and metabolite data obtained under contrasting growth conditions using principal component analysis suggests that, with the exceptions of alanine amino transferase and glutamate and malate dehydrogenase and malate, there are no links between single enzyme activities and metabolite time courses or levels.

Is change in ovary carbon status a cause or a consequence of maize ovary abortion in water deficit during flowering?

“…Aliquots of 20 mg fresh weight were extracted as described by Biais et al (2014), and enzyme activities were measured according to Gibon et al (2004Gibon et al ( , 2006Gibon et al ( , 2009, Sulpice et al (2007), and Biais et al (2014). Assays for neutral invertase and acid invertase were performed after desalting (PD Multitrap G-25; GE Healthcare).…”

Modelling central metabolic fluxes by constraint‐based optimization reveals metabolic reprogramming of developing Solanum lycopersicum (tomato) fruit

“…A network comprised of 71 metabolic conversions including energetic processes can explain the main biological activity required for the biosynthesis of the main biomass components. A comprehensive data set for fruit biomass components (Biais et al ., 2014) has been used to set up the constraints of the external fluxes at each stage of development. The results of the stoichiometric modelling are presented as metabolic states occurring at three main physiological transitions of fruit development, i.e.…”

Genome-Wide Association Mapping Reveals That Specific and Pleiotropic Regulatory Mechanisms Fine-Tune Central Metabolism and Growth in Arabidopsis

“…Proxies for enzyme abundance can be obtained by determining in vitro enzyme activity, using assay conditions that detect maximum activity (Stitt and Gibon, 2014). While conventional enzyme assay methods are slow, robotized platforms have been established that provide accurate measurements of many enzymes in a large number of samples (Gibon et al, 2004b;Keurentjes et al, 2008;Steinhauser et al, 2011;Biais et al, 2014;Toubiana et al, 2016).…”