Effect of grapevine leafroll associated virus 3 (GLRaV-3) on berry composition of Vitis vinifera L. cv. Sauvignon blanc

Abstract

Grapevine leafroll associated virus 3 (GLRaV-3) is a phloem limited virus that is one of the most important viruses affecting grapevines as it is associated with significant economic losses in many vineyards around the world. In order to determine the effects of GLRaV-3 on fruit composition and wine chemical profile of must and wine from Vitis vinifera L. cv. ‘Sauvignon Blanc’ grown in New Zealand, parameters such as grape ripeness and color index were measured during the summer 2014 on fruit from vines either infected with GLRaV-3 (established or recent infections) or uninfected vines. Established infections were identified prior to 2008 whereas recent infections were only identified subsequently. In addition, physiological parameters and vine yield were determined from the same plants. Physiological ripeness (20.4ºBrix) was the criterion established to determine the harvest date for each of the three vine infection statuses. Date of grape ripeness was strongly affected by virus infection; both infected plant groups had harvest delayed by more than one week compared with the GLRaV-3 uninfected plants, indicating possible impacts on assimilate transport. Net photosynthesis and stomatal conductance decreased in the virus infected plants compared with uninfected plants; however, there were no differences between established and recently infected groups. In must and wine, GLRaV-3 infection prior to 2008 reduced titratable acidity (0.89 g/L) compared with the uninfected control. Differences observed in fermentation curves from the three infection status groups did not modify basic wine chemical properties. In conclusion, GLRaV-3 infection slowed grape ripening, yet harvested ripe grapes resulted in minimal effects on the must and wine chemistry. Time of infection produced differences in specific plant physiological parameters; however, these did not produce measurable impacts on the wine when harvest was delayed to allow fruit to reach commercial maturity.