Cold storage induces different metabolic responses in peach fruits with different harvest time

BUSTAMANTE, CLAUDIA; MONTI, LAURA; GABILONDO, JULIETA; BUDDE, CLAUDIO OLAF; FERNIE, ALISDAIR R; LARA, MARÍA VALERIA; DRINCOVICH, MARÍA FABIANA

Salta

Congreso; LV Reunión Anual de SAIB - XIV PABMB. 2019.; 2019

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Peaches ripen and deteriorate quickly at room temperature. Therefore, refrigeration is used to slow these processes and to extend fruit market life; however, several fruits can develop chilling injury (CI) during storage at low temperature. CI symptoms mainly develop during fruit ripening after cold storage, so this problem is not perceived until the fruit reaches consumers. Hence, the molecular reconfiguration that takes place during cold storage impacts on the way fruits ripen during the following shelf-life, situation that limits commercialization of these fruits. In this study, a metabolite profiling study of six peach varieties with different agronomic characteristics was performed after ripening, either following cold treatment or not, in order to evaluate the effects of refrigeration on the levels of metabolites involved in organoleptic properties and protection against stress. By using GC-MS, 51 polar metabolites were detected in Flordaking (FD), Rojo 2 (R2), Springlady (SL), Red Globe (RG), Elegant Lady (EL) and Limón Marelli (LM) varieties when fruits were stored at 20ºC until reaching firmness and organoleptic characteristics suitable for consumption (SL), and after cold storage at 0ºC for 21 days followed by ripeness at 20ºC (CS+SL). The identified metabolites were divided into sugars, sugar alcohols, organic acids, amino acids, fatty acids and miscellaneous compounds. Interestingly, xylose was the only metabolite that increased in CS+SL fruits, in relation to SL samples, in all the varieties analyzed, indicating a particular reconfiguration of the cell wall after cold storage. PCA analysis revealed interesting results. The first principal component (PC1, 38.7% of the variance) separated the samples depending on harvest time, with mid & late varieties on the positive and early varieties on the negative side, independently to whether the fruits were resistant or susceptible to CI. Among the metabolites that most contribute to PC1 separation, higher levels of maltose, maltitol and fructose 6-P were found in mid & late varieties, while higher levels of Thr, Ile and Val were found in early varieties. PC2 and PC3 did not contribute to separate the samples in any biologically meaningful group. HCA showed similar results, although a clear separation of SL and CS+SL samples in EL variety could be observed, which were fruits characterized by a large increase in sugars like sucrose, glucose and fructose, and organic acids such as citrate, malate, and quinate after refrigeration. Overall, the results showed a differential restructuration of peach fruit metabolism following exposure to cold in varieties with different harvest time. In particular, the identification of the molecular basis of the particular response of EL to cold is a future challenge, since it could aid in defining strategies for the improvement of the organoleptic quality of peach fruits by increasing sugar and organic acids levels while fruits are stored at low temperatures.