Bailey Hallwachs, Bhaskar Bondada,* Marc Fuchs, Sadanand Dhekney, Benham Khatabi, Alexander Levin, and Patricia Skinkis
*Washington State University Tri-Cities, 2710 Crimson way, Richland, WA 99354 (bbondada@wsu.edu)

Red blotch disease, caused by Grapevine red blotch-associated virus (GRBaV), is a recent addition to the extensive repertoire of viruses that infect grapevines. Infection results in red blotches on leaves with pinkish red-colored veins without rolling off the margins observed at the onset of ripening in red cultivars. The objective of this study was to gain an understanding of the onset of systemic infection of the red blotch virus to aid designing antiviral interventions by examining fruit quality attributes and various tissues of healthy and afflicted vines with microscopy. The fruit quality of afflicted vines was compromised, as indicated by reduced Brix, high pH, and reduced vigor. This indicated that the virus blocks the sugar pathway (phloem tubes), impeding translocation of sugars into the berries during ripening. While leaf structural architecture was not affected, the infected chloroplasts developed plastoglobuli, tannins in addition to a massive accumulation of starch. Some chloroplasts were completely dismantled. Furthermore, the infected vines developed clusters of hens and chickens and altered seed morphology. On the other hand, the healthy seeds were pyriform with a distinct beak. The study showed that red blotch virus infection lowers fruit quality by altering the structural integrity of the vine system.

Funding Support: Oregon Wine Board