Metabolite and proteome changes during the ripening of Syrah and Cabernet Sauvignon grape varieties cultured in a nontraditional wine region in Brazil

Abstract

Grapevines are an important fruit crop from economic and cultural point of views in many countries, including Brazil, where the practice of vitiviniculture is being developed in different regions. We compared the anthocyanin concentration, the main organic acids and sugars, and the proteome profiles during berry ripening of Syrah and Cabernet Sauvignon grapes from two distinct geographical sources in São Paulo State. The proteome was mapped by two-dimensional gel electrophoresis and differentially abundant proteins during the ripening process were subjected to MALDI-TOF/TOF-MS analysis. An increase in sugar concentration and in anthocyanin content was observed, as well a decrease in the tartaric and malic acid concentration. A total of 128 spots varied with geographical origin, grape variety, and ripening stage, with 108 being identified. The identified proteins resulted in 80 gene products. A multivariate analysis of protein abundance clustered the samples according to grape variety, geographical origin, and stage of ripening, and showed the possibility of using proteomics to characterize three variables: variety, area where grown, and the ripening process. The changes observed during the ripening process corresponded to enzymes involved in sugar and organic acid metabolism. These results are in accordance with the metabolic profile reported for the process. Given the importance of discriminating grapes, thus making the adulteration of wines more difficult, in this paper we showed the possibility of differentiating varieties of grapes, geographical area of cultivation and stage of ripening by combining the results of differentially abundant protein determinations and multivariate analysis.