Grapevine viruses: friend or foe for quality viticulture? A case study from Trentino

Abstract

Grapevine viruses represent a critical challenge in many viticultural districts, significantly undermining vine productivity and longevity. Despite this, it is still debated whether such infections might paradoxically enhance quality. To verify this hypothesis, this study investigated the impact of GPGV, GFLV, GLRaV-1, and GLRaV-3 mixed infections on Pinot gris performance in Trentino (Italian Alps). Molecular tests (ELISA, RT-PCR) highlighted widespread mixed infections, likely resulting from infected nursery material and vectors. Comparing healthy and infected plants revealed significant differences: infections caused a drastic reduction in cluster weight (mean 198 g vs 49 g, -80 %). Chemical analyses confirmed a qualitative shift, with generally higher total acidity and lower sugars. However, the impact depended on the viral mix: GPGV/GFLV/GLRaV-3 was the most detrimental, whereas the GPGV/GFLV/GLRaV-1 combination remained surprisingly similar to healthy grapes. Micro-fermentations (by selected S. cerevisiae strain and controlled environmental condition, without grape must modification) showed significantly higher viable yeast counts in healthy musts. While CO₂ production rates (estimated by Gompertz model) were similar, infected samples showed a delayed lag phase. Finished wines mirrored the musts: GFLV/GLRaV-3 trials resulted in lower alcohol and elevated acidity, confirming that specific co-infections compromise oenological suitability. GC-MS/MS analysis also verified distinct aromatic profiles from virus affected and safe samples. In conclusion, viral associations not only reduce productivity and lifespan but also deteriorate grape quality, debunking the myth of qualitative improvement. While targeted nutrition is advisable, strict sanitary control of nursery material remains the primary defence.

References

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Gualandri, V., Asquini, E., Bianchedi, P., Covelli, L., Brilli, M., Malossini, U., Bragagna, P., Saldarelli, P., & Si-Ammour, A. (2017). Identification of herbaceous hosts of the Grapevine Pinot gris virus (GPGV). European Journal of Plant Pathology, 147(1), 21–25. https://doi.org/10.1007/s10658-016-0989-4