Grapevine red blotch virus alters grape skin cell-wall composition impacting phenolic extractability during winemaking

Authors: Rumbaugh, Arran; MEDINA-PLAZA, CRISTINA - University Of California, Davis; Sudarshana, Mysore; OBERHOLSTER, ANITA - University Of California, Davis

Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2023
Publication Date: 2/20/2023
Citation: Rumbaugh, A.C., Medina-Plaza, C., Sudarshana, M.R., Oberholster, A. 2023. Grapevine red blotch virus alters grape skin cell-wall composition impacting phenolic extractability during winemaking. Journal of the Science of Food and Agriculture. 103(7):3457-3467. https://doi.org/10.1002/jsfa.12481.
DOI: https://doi.org/10.1002/jsfa.12481

Interpretive Summary:

Technical Abstract: Grapevine red blotch virus (GRBV) is the causal agent of grapevine red blotch disease and is known to delay grape ripening. However, grape cell wall modifications during GRBV infection are largely unknown, even though the cell wall plays a large roll in pathogenicity, viral interactions with host plants, and phenolic extractability during winemaking. Understanding the impact of GRBV infection on cell wall metabolism is important for the development of potential mitigations strategies. In this study, high-throughput transcriptome sequencing was conducted on Vitis vinifera L. Merlot grapes during ripening. The cell wall composition, phenolic content, and phenolic extractability at two different commercial harvest points were also determined. Log fold changes indicated a strong induction in diseased grapes at harvest of several transcripts involved in cell wall solubilization and degradation. However, these observations did not translate to changes in cell wall composition at either harvest point in diseased grapes potentially suggesting post-transcriptional regulation. Moderate induction of pectin methylesterase inhibitor transcripts and transcripts associated with pathogenesis-related proteins coincided with increases in pectin and soluble proteins in cell walls of diseased grapes at harvest. Both pectin and pathogenesis-related proteins are known to retain phenolic compounds during winemaking. Our study confirmed this when the percent extractability of flavonols in wines was significantly lower when made from GRBV infected fruit. These finding suggests GRBD alters the grape cell walls, consequently leading to phenolic retention during winemaking.