Identification and genetic diversity of grapevine virus L in Greece.

In this study, grapevine virus L (GVL) was identified for the first time in Greece through the application of high-throughput sequencing of total RNA from grapevine samples. Further investigation of the prevalence of GVL in Greek vineyards by RT-PCR revealed its presence in 5.5% (31/560) of the tested samples, which originated from six viticultural areas of the country. Comparative sequence analysis based on the CP gene revealed a high degree of genetic variability among GVL isolates, while phylogenetic analysis grouped the Greek isolates in three of the five phylogroups formed, with most of them being classified in phylogroup I.

Prevalence and Genetic Diversity of Viruses Associated with Rugose Wood Complex in Greek Vineyards.

Rugose wood is one of the most important disease syndromes of grapevine, and it has been associated with at least three viruses: grapevine rupestris stem pitting-associated virus (GRSPaV), grapevine virus A (GVA), and grapevine virus B (GVB). All three viruses show a worldwide distribution pattern, and their genetic composition has been the focus of extensive research in past years. Despite their first record in Greece almost 20 years ago, there is a lack of knowledge on the distribution and genetic variability of their populations in Greek vineyards. In this context, we investigated the distribution of GRSPaV, GVA, and GVB in rootstocks, self-rooted vines, and grafted grapevine cultivars originating from different geographic regions that represent important viticultural areas of Greece. Three new reverse transcription-PCR assays were developed for the reliable detection of GRSPaV, GVA, and GVB. Our results indicated that GVA is the most prevalent in Greek vineyards, followed by GRSPaV and GVB. However, virus incidence differed among self-rooted and grafted grapevine cultivars or rootstocks tested. Selected isolates from each virus were further molecularly characterized to determine their phylogenetic relationships. All three viruses exhibited high nucleotide diversity, which was depicted in the constructed phylogenetic trees. Isolates from Greece were placed in various phylogroups, reinforcing the scenario of multiple introductions of GVA, GVB, and GRSPaV in Greece and highlighting the effect of different transmission modes in the evolutionary course of the three viruses.

The complete genome sequence of a divergent grapevine virus I isolate naturally infecting grapevine in Greece.

A significant number of new members of the genus Vitivirus have been identified recently, mainly due to the advent of high-throughput sequencing (HTS). Grapevine virus I (GVI), which was identified in New Zealand in 2018, is one of these viruses. RNAseq HTS analysis of a Greek grapevine (cv. Daphnia), revealed the presence of a GVI-like isolate (D2-1/19). Sequence analysis confirmed the classification of D2-1/19 as GVI. However, both sequence and phylogenetic data exhibited high levels of variability between D2-1/19 and the previously characterized GVI isolates. This study provides the full-length sequence of a divergent GVI isolate, adding knowledge to the limited information available about this recently identified virus.