Grapevine red blotch virus is sporadically present in a germplasm collection in Northern Italy

Limited information is available on the distribution of grapevine red blotch virus (GRBV) in grape-growing regions outside North America. In this study, the presence of GRBV was investigated in 596 grapevine samples coming from different sources in Northern Italy, including rootstock and table grape accessions from ampelographic collections, and commercial varieties with red blotch-like symptoms. Only ‘Queen’ and ‘Incrocio Dalmasso VIII-5’ accessions, collected from the CREA-Viticulture and Enology repository of table grape varieties, tested positive for GRBV. Sequencing of fragments from replication and coat protein genes revealed that the two accessions were infected with GRBV isolates belonging to two distinct lineages. While the American origin of ‘Queen’ could explain the GRBV presence in this accession, the viral infection of the Italian ‘Incrocio Dalmasso VIII-5’ remains an unsolved mystery.