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ARS Home » Pacific West Area » Davis, California » Crops Pathology and Genetics Research » Research » Publications at this Location » Publication #429044
Research Project: Improved Pest and Disease Control for Enhanced Woody Perennial Tree Crop and Grapevine Production

Location: Crops Pathology and Genetics Research

Title: Temporal dynamics of Grapevine red blotch virus accumulation in grapevine leaves is influenced by fruit maturity stages

Author
item SINGH, PREM - University Of California, Davis
item REDDY, KISHOREKUMAR - University Of California, Davis
item SCULLY, HAZEL - University Of California, Davis
item BOGHOZIAN, ARPA - University Of California, Davis
item MEDINA-PLAZA, CRISTINA - University Of California, Davis
item OBERHOLSTER, ANITA - University Of California, Davis
item Sudarshana, Mysore

Submitted to: Archives of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/13/2026
Publication Date: 5/20/2026
Citation: Singh, P.P., Reddy, K., Scully, H., Boghozian, A.M., Medina-Plaza, C., Oberholster, A., Sudarshana, M.R. 2026. Temporal dynamics of Grapevine red blotch virus accumulation in grapevine leaves is influenced by fruit maturity stages. Archives of Virology. 171, 183 (2026). https://doi.org/10.1007/s00705-026-06634-0.
DOI: https://doi.org/10.1007/s00705-026-06634-0

Interpretive Summary: This manuscript describes the results of a collaborative study on the effect of fruit maturity stages on temporal changes in the titer of grapevine red blotch virus (GRBV) determined by digital PCR. The study involved Merlot grapevines in a Central coast vineyard which were initailly free from GRBV, but got infected in 2016, 2019, 2020, and 2021. The virus titer in these grapevines were determined in 2021 and 2022 at four maturity stages, pre-véraison, véraison, post-véraison, and harvest. The results indicate that the virus titer was generally highest at harvest. The length of infection in years, did not have much influence on virus titer. High virus titers make grapevines accessible for virus acquisition by vectors for prolonged period during the season. For diagnosis, petiole samples can be collected from pre-véraison through rest of the season. Our results fill a critical gap indicating a lack of a role of virus titer on foliar symptom expression.

Technical Abstract: Grapevine red blotch disease (GRBD) poses a serious threat to viticulture in the United States. Grapevine red blotch virus (GRBV), a member species of Grablovirus vitis (family Geminiviridae), the causal agent of GRBD, disrupts grapevine physiology and metabolism, thereby interfering with the natural processes of fruit ripening. To date, there is limited knowledge about how grape maturity stages influence the timing of changes in viral load and disease progression. This study elucidates the effect of fruit maturity stages on GRBV accumulation in Vitis vinifera L. cv. Merlot grapevines in a Central Coast vineyard in California. Petioles from six basal leaves at random from previously GRBV-infected vines were collected at pre-véraison, véraison, post-véraison, and harvest stages, across two years (2021 and 2022). The viral copy number was quantified using digital PCR. The study identified significant differences (p'<'0.05) in GRBV copy number across different maturity stages in 2021, irrespective of the year of infection. The lowest viral load was observed during the pre-véraison stage, and the highest at harvest, indicating progressive viral accumulation as the grapevines development progressed. In 2022, however, no significant difference in viral load across maturity stages was detected, an outcome attributed to extreme heat spikes coinciding with sampling periods. Our findings highlight the interplay between GRBV accumulation, grape development, and environmental parameters.