Ultrastructural and Compositional Analyses of Grapevines Infected with Red Blotch Virus
Bhaskar Bondada,* Bailey Hallwachs, 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 severe concern to grapegrowers and winemakers in the Pacific Northwest, including California. One key aspect of all viruses, including Red Blotch, is their intimate association with cell components and anomalous structures following infection. Therefore, the objective of this study was to analyze the fruit quality and ultrastructure of various tissues and document the relationship of ultrastructural cytopathology with the GRBaV infection in Pinot noir employing various microscopy techniques. The infected vines exhibited typical red blotches in leaves, with pinkish red-colored veins, without rolling off the margins at the onset of ripening. The infected vines developed clusters of hens and chickens and altered seed morphology. Conversely, the healthy seeds were pyriform with a distinct beak. The infection significantly altered the primary and secondary metabolites desired for making wine. Since postveraison berry development and ripening relies on phloem influx, the altered metabolism was indicative of a disruption of the phloem pathway, either in the source leaf or in the berries. While the infected vines maintained primary leaf anatomical organization, the chloroplasts underwent significant ultrastructural changes, ranging from complete dismantling to massive accumulation of starch, plastoglobuli development, and tannins in the cytoplasm. The study demonstrated that structural integrity is key to maintaining the normal metabolism of the grapevine.
Funding Support: NCSFR
