A proteometabolomic study of Actinidia deliciosa fruit development

Green-fleshed kiwifruit is worldwide appreciated for its flavor and macronutrients that are related to its physiological development. Fruit ripe stage for harvesting does not correspond to an optimal edible condition due to firmness/acidity pome characteristics; this is overcome with postharvest fruit processing. To describe the metabolic pathways/molecular effectors underlying Actinidia deliciosa cv. Hayward pome physiological development, kiwifruits were harvested at four growth stages (from fruit set to physiological maturity), and corresponding outer endocarp samples were analysed for metabolite and protein content. Combined NMR/LC-UV/ESI-IT-MSn procedures quantified 46 metabolites at these developmental stages; similarly, integrated 2D-DIGE/nLC-ESI-LIT-MS/MS analyses described corresponding proteomic changes. Quantitative protein dynamics showed that components related to disease/defense, protein destination/storage, metabolism, energy and cell structure functions were highly affected at specific moments of fruit development, suggesting a rationale to pomological and metabolite content characteristics at those times. Bioinformatic interaction prediction revealed a main network of differentially represented proteins, which may control metabolic changes in developing kiwifruit. Main pome allergens were also quantified, demonstrating their highest levels at the mature stage. By aligning kiwifruit development to a proteometabolomic representation, this investigation integrates previous metabolic observations and provides a reference framework for further physiological/nutritional studies, also allowing cross comparison among crop species.