Impact of viral infection on physicochemical, phenolic and volatile composition of ‘Cabernet Sauvignon’ grapes and wines

Viruses are one of the most important biotic factors affecting grapevines and the wine sector around the world. In Brazil, three viruses are the most important. The purpose of this study was to evaluate the effect of the presence of grapevine leafroll-associated virus 3 (GLRaV-3), grapevine virus A and grapevine virus B (GVA and GVB are implicated in the etiology of the grapevine rugose wood complex), on agronomical parameters of ‘Cabernet Sauvignon’ vines and metabolic profiles of grapes and wines. Viruses reduced the yield and sugars and increased total acidity in grapes. The anthocyanins and flavan-3-ols were reduced in grapes from diseased vines, while trans-resveratrol, flavonols and caftaric acid increased in these grapes. Viruses reduced the most prominent anthocyanins, flavan-3-ols, flavon-3-ols and caftaric acid in wines from diseased vines, while increased taxifolin and trans-resveratrol. The volatile compounds were reduced in wines from diseased vines. Multivariate analysis showed that phenolic and volatile compounds in wines presented the highest percentage of discrimination among diseased and healthy vines.