An overview on grapevine viruses, viroids, and the diseases they cause

Abstract

Nearly 70 different viruses have been identified in grapevines (Vitis and Muscadinia sp.), about half of which (31 viruses) are associated with the four major disease complexes known as (1) infectious degeneration (12 Eurasian/European/ Mediterranean nepoviruses) and decline (four American nepoviruses), (2) leafroll (five viruses), (3) rugose wood (six viruses), and (4) fleck (four viruses). By contrast, seven grapevine-infecting viroids are known, of which only two induce visible symptoms. Most of the viruses have single-stranded RNA genomes either of positive or negative sense which are encapsidated in isometric or filamentous particles. A few of these viruses have a double-stranded RNA genome, and, very recently, viruses with a DNA genome have emerged. Vectors include dorylamoid nematodes, pseudoccocid mealybugs, soft scale insects, eriophyid mites, and a treehopper. A brief historical account of the major disease complexes is given and of the presumptive origins of their recognized or putative agents.