Primary metabolite fruit profile is altered in response to source-sink imbalance and can be used as early quality predictors in nectarine

Abstract

Peaches and nectarines are among the most exported fresh fruits from Chile. Fruit acceptance by final consumers is defined by quality parameters as size, taste, color and juiciness. In these fruits the balance between soluble sugars present in the mesocarp and organic acids determines the taste. Biomass production and metabolites accumulation by fruits occur during different developmental stages and depend on photosynthesis and carbon exportation by source leaves. Carbon supply to fruits can be potentiated through field practices of thinning (removal of flowers/fruits) that lead to change in source-sink balance. It is well known that thinning leads to fruits with increased size, but it is not known how this practice could influence fruit quality in terms of metabolite composition. In this work, we analyzed primary metabolite of nectarine cv‘Magique’ at different developmental stages and from trees submitted to thinning. Fruit mesocarp primary metabolites were analyzed across the whole development until harvest and subsequently postharvest ripening. Sugars, amino acids and organic acids were measured by 1H-NMR,HPAEC-PAD and HPLC-DAD. In addition, harvest and ripening quality parameters as size, juiciness and brix was performed. We observed that fruits from thinned trees had better quality parameters than unthinned trees. Our results also indicated that thinning affects metabolic composition from early through late developmental stages. Principal component analysis of phenotypic and metabolic data at different stages of development and thinning revealed that glucose, fructose, sucrose, inositol, galactose and succinate concentrations at early stages of development (S1 and S2 stages) can be used to segregate fruits with higher quality. In conclusion, we suggest that profile of these metabolites in early stages of development could be a metabolic predictor of final fruit quality in nectarines.