Protein analysis of moro blood orange pulp during storage at low temperatures

A protein analysis in the pulp of Moro blood oranges (Citrus sinensis L. Osbeck) at the onset and after 30 days of storage at either 4 or 9 °C was performed. All differential proteins belonged to different functional classes (sugar, amino acid and secondary metabolism, defense, stress response, oxidative process, transport and cellular component biogenesis), displaying a differential accumulation in those Moro oranges kept at 9 versus 4 °C, and in those stored at 4 °C versus onset. Anthocyanin biosynthesis structural proteins chalcone synthases and flavonone 3-hydroxylase and different glutathione S-transferases related with their vacuolar transport were up-accumulated in fruits kept at 9 versus 4 °C and versus the onset. Proteins related with defense and oxidative stress displayed a similar pattern, concomitant with a higher anthocyanin content, denoting a possible role of defense and other stress response pathways in anthocyanin production/accumulation.