Proteomic analysis of orange fruits affected by heat treatment and different postharvest storage periods

PEROTTI, V.E.; DEL VECCHIO, H.; MEIER, G.; BELLO, F.; COCCO, M.; VÁZQUEZ, D.; PODESTÁ, F.E.

Lisboa

Congreso; 28th International Horticultural Congress; 2010

The INTERNATIONAL SOCIETY FOR HORTICULTURAL SCIENCE

Heat treatment or curing is a common procedure prior to long time storage of citrus fruits. The aim of this study was to characterize changes at the molecular level induced by heat treatment on the proteome of orange fruit (Citrus sinensis L. Osbeck). Following two-dimensional PAGE, more than 50 differential protein spots were detected in juice vesicle tissue among all comparisons made. Heat treatment significantly affected the abundances of 16 proteins, while 25 differential proteins were found along the storage period. Identification of these citrus proteins by mass spectrometry and annotation according to the NCBI and Viridiplantae ESTs data bases revealed that 27% were stress-related proteins involved in cell rescue, defense and virulence, 24% were involved in metabolism, 20% were found to be storage proteins, and 15% belonged to the biogenesis of cellular components; being the rest related to minor categories. The analysis of metabolites in flavedo showed an increase in sugar levels while, in turn, organic acids decreased markedly. Putrescine was only detected in treated flavedo, demonstrating the activation of defense mechanisms in this tissue. In order to analyse the changes produced in the antioxidant metabolism different enzyme activities were performed on both tissues. Results obtained in this respect would correlate to the absence of visual injuries in the fruit surface and would explain a defense response, involving H2O2 as a secondary messenger within the fruit. In conclusion, the present study provides the first analysis at the molecular level of citrus fruit responses to heat treatment.