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 over the 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 and grafted grapevine cultivars, originating from different geographic regions that are representing important viticultural areas of Greece. Three new RT-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.
Grapevine virus A variants of group II associated with Shiraz disease in South Africa are present in plants affected by Australian Shiraz disease, and have also been detected in the USA