Grapevine Leafroll: A Complex Viral Disease Affecting a High-Value Fruit Crop

Abstract

Grapevine (Vitis spp.) is one of the most widely grown fruit crops in the world. It is a deciduous woody perennial vine for which the cultivation of domesticated species began approximately 6,000 to 8,000 years ago in the Near East. Grapevines are broadly classified into red- and white-berried cultivars based on their fruit skin color, although yellow, pink, crimson, dark blue, and black-berried cultivars also exist. Grapevines can be subject to attacks by many different pests and pathogens, including graft-transmissible agents such as viruses, viroids, and phytoplasmas. Among the virus and virus-like diseases, grapevine leafroll disease (GLD) is by far the most widespread and economically damaging viral disease of grapevines in many regions around the world. The global expansion of the grape and wine industry has seen a parallel increase in the incidence and economic impact of GLD. Despite the fact that GLD was recognized as a potential threat to grape production for several decades, our knowledge of the nature of the disease is still quite limited due to a variety of challenges related to the complexity of this virus disease, the association of several distinct GLD-associated viruses, and contrasting symptoms in red- and white-berried cultivars. In view of the growing significance of GLD to wine grape production worldwide, this feature article provides an overview of the state of knowledge on the biology and epidemiology of the disease and describes management strategies currently deployed in vineyards.

Grapevine Virus Diseases:economic Impact and Current Advances in Viral Prospection and Management

“…Viral disease effects in grapevines can manifest in more specific or more comprehensive forms, with variations that depend on the viral species or strains, grapevine cultivar and agronomic or climatic conditions. Infected plants exhibit changes in genes expression profile, carbohydrate metabolism and hormonal balances, decrease in photosynthetic potential, increase in respiration rate, interference in electron transport activity of photosystem I and II, reduction of the chlorophyll levels and soluble sugar accumulation in the leaves and deficiency in translocation of these sugars to sink tissues or grape berries (BASSO et al, 2010c;NaIDu et al, 2015).…”

“…These stresses have effects in berry quality because of irregular ripening and affect plant growth resulting in a delay of sprouting, reduced tolerance to stresses and even death of the chronically infected plants (cReTaZZO et al, 2010 andGIRIBalDI et al, 2011;NaScIMeNTO et al, 2015;VeGa et al, 2011). Grapes harvested from infected grapevines show reduced total soluble solid content (from 3 to 5 ºBrix), color intensity of red-berried cultivars of up to 35%, total polyphenol content of up to 38%, biosynthesis of tannins, flavonoids, anthocyanins, polyamines, aromatic compounds and other metabolites, and increase in titratable acidity of the must (alaBI et al, 2016;BaSSO et al, 2010c;GuTha et al, 2010;NaIDu et al, 2015). a recent study in the uSa estimated that the economic impact of grapevine leafroll disease on the profit of grape businesses range from $25,000 to $40,000 per hectare for vineyards with a 25-year lifespan (aTallah et al, 2012).…”

“…Grapevine leafroll disease (GLRD): GlRD is the most economically damaging and widespread viral disease of grapevine throughout the world (alaBI et al, 2016;alMeIDa et al, 2013;aTallah et al, 2012;NaIDu et al, 2014 and. It can cause up to 40% yield losses (NaIDu et al, 2014).…”

“…Grapevine leafroll, rugose wood complex, leaf degeneration and fleck disease are the four main disorders having a worldwide economic importance (ANDRET-LINK et al, 2004;NaIDu et al, 2015). Grapevine viruses associated with these diseases have a RNa genome.…”

“…Therefore besides the experience in recognizing the symptoms caused by these pathogens, the availability of efficient detection techniques is important. Recent advances in molecular biology tools to study the viral population present in vineyards, allowed the efficient detection, identification and prospection of known or new viral species and strains (al RWahNIh et al, 2015;MAREE, 2015;ROOSSINCK et al, 2015). using next-generation sequencing technologies (NGS) (al RWahNIh et al, 2015) and rolling-circle amplification (RCA) strategies (INOue-NaGaTa et al, 2004) have enhanced the diagnosis tools and knowledge of grapevine virome (al RWahNIh et al, 2013b;BaSSO et al, 2015;GIAMPETRUZZI et al, 2012;MALIOGKA et al, 2015b).…”