Grapevine Red Blotch Virus May Reduce Carbon Translocation Leading to Impaired Grape Berry Ripening

Grapevine red blotch virus (GRBV) is suspected to alter berry ripening and chemistry. This study performed a physiological characterization of GRBV infected grapevines with attention to the factors leading to chemical changes during ripening of Cabernet Sauvignon in two rootstocks, 110R and 420A. RB(+) grapevines had transiently lower net photosynthesis; however, berry total soluble solids (TSS) accumulation was consistently reduced in the two years of study. Accumulation of anthocyanins and loss of titratable acidity and proanthocyanins were also delayed in RB(+) plants. However, the comparison of samples with the same TSS led to lower pH and anthocyanins content. The reduction in carbon import into berries under mild and transient reductions in carbon fixation suggested an impairment of translocation mechanisms with RB(+), leading into a desynchronization of ripening-related processes.