Viruses (Jun 2022)

Nuances of Responses to Two Sources of Grapevine Leafroll Disease on Pinot Noir Grown in the Field for 17 Years

  • Jean-Sébastien Reynard,
  • Justine Brodard,
  • Vivian Zufferey,
  • Markus Rienth,
  • Paul Gugerli,
  • Olivier Schumpp,
  • Arnaud G. Blouin

DOI
https://doi.org/10.3390/v14061333
Journal volume & issue
Vol. 14, no. 6
p. 1333

Abstract

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Grapevine leafroll disease (GLD) is one of the most economically damaging virus diseases in grapevine, with grapevine leafroll-associated virus 1 (GLRaV-1) and grapevine leafroll-associated virus 3 (GLRaV-3) as the main contributors. This study complements a previously published transcriptomic analysis and compared the impact of two different forms of GLD to a symptomless control treatment: a mildly symptomatic form infected with GLRaV-1 and a severe form with exceptionally early leafroll symptoms (up to six weeks before veraison) infected with GLRaV-1 and GLRaV-3. Vine physiology and fruit composition in 17-year-old Pinot noir vines were measured and a gradient of vigor, yield, and berry quality (sugar content and berry weight) was observed between treatments. Virome composition, confirmed by individual RT-PCR, was compared with biological indexing. Three divergent viromes were recovered, containing between four to seven viruses and two viroids. They included the first detection of grapevine asteroid mosaic-associated virus in Switzerland. This virus did not cause obvious symptoms on the indicators used in biological indexing. Moreover, the presence of grapevine virus B (GVB) did not cause the expected corky bark symptoms on the indicators, thus underlining the important limitations of the biological indexing. Transmission of GLRaV-3 alone or in combination with GVB by Planococcus comstocki mealybug did not reproduce the strong symptoms observed on the donor plant infected with a severe form of GLD. This result raises questions about the contribution of each virus to the symptomatology of the plant.

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