Idaho 'Cabernet Sauvignon' grape composition altered by grapevine leafroll-associated virus 3

This is the first report of how grapevine leafroll-associated virus 3 (GLRaV-3) infected vines impact Idaho grown 'Cabernet Sauvignon' grape quality. A single block of plants selected based on molecular testing, with pairs of healthy and GLRaV-3 infected vines, was examined for grape quality for three consecutive growing seasons. Grapes from GLRaV-3 infected vines had significantly higher concentrations of total organic acids (both tartaric acid and malic acid were elevated), and were significantly lower in total anthocyanins (10 mg/100 g difference), total phenolics (40 mg/100 g difference), total tannins (63 mg/100 g difference), and total free amino acids (43 mg/kg difference; nine free amino acids) compared to healthy vines. Cluster weights and concentrations of total sugars (glucose and fructose), and yeast assimilable nitrogen content, were not different between healthy and infected vines. Based on these findings, some quality elements of Idaho 'Cabernet Sauvignon' grapes important in wine production were negatively impacted by GLRaV-3 infection.