Grapevine fleck and similar viruses

Abstract

Grapevine fleck virus (GFkV), grapevine red globe virus (GRGV), grapevine rupestris vein feathering virus (GRVFV), grapevine asteroid mosaicassociated virus (GAMaV), and grapevine Syrah virus 1 (GSyV-1) are a group of evolutionarily related viruses with similar morphological, physicochemical, and molecular properties. GFkV is the agent of fleck disease, and GAMaV and GRVFV are associated with asteroid mosaic and vein feathering diseases, respectively, while GRGV is not involved in any specific symptomatology. GSyV-1 is included in this chapter as it shares many traits with the four aforementioned viruses, but has not yet been associated with any particular syndrome. All these viruses are phloem limited, nonmechanically transmissible, and primarily spread through infected propagating material. GFkV is ubiquitous, while the other viruses have been reported only from certain geographical areas. Despite few unconfirmed reports of natural field transmission of GFkV, no vector has been identified for it, nor any of the other viruses. Viral genomes consist of a single molecule of a capped and polyadenylated, cytosine- rich, messenger-like RNA 6.5-7.5 kb in size. According to the current taxonomy, these viruses belong to recognized or putative species in the genera Maculavirus (GFkV and GRGV) and Marafivirus (GSyV-1, GRVFV, and GAMaV) in the family Tymoviridae, order Tymovirales.