Virome of the Russian Grapevine Germplasm: A Final Study and Summary.

Ampelographic collections play an important role in the conservation of grapevine genetic resources and therefore require continuous phytosanitary monitoring. In this study, the virome of grapevines from the Magarach ampelographic collection in Russia was analyzed using total RNA high-throughput sequencing. A total of twenty-seven grapevine viruses and four viroids were identified. Two viruses were characterized as putative novel species: (+) ssRNA grapevine umbra-like virus 5 (GULV-5) and the bipartite (+) ssRNA grapevine Magarach secovirus (GMSV), which, together with related viruses, may represent a novel genus within the family Secoviridae. Among the economically important viruses, the most prevalent were grapevine fanleaf virus (76%), grapevine leafroll-associated virus 1 (39%), and grapevine virus A (33%). Mixed infections involving two or three of these viruses were detected in 50% of the analyzed grapevines. Grapevine virus D was detected in Russia for the first time. Phylogenetic analysis of 222 assembled virus and viroid genome sequences revealed high genetic diversity. The obtained results were summarized and compared with previous virome studies conducted on four Russian ampelographic collections.