A review of the ecology of grapevine leafroll associated virus type 3 (GLRaV3)

Abstract

Grapevine leafroll disease in New Zealand is predominantly caused by the ampelovirus GLRaV3 which is vectored between vines by up to three species of mealybugs (Pseudococcus spp) However global understanding of the transmission and spread of GLRaV3 remains limited and does not definitively show how to successfully manage the disease in New Zealand The disease is a manifestation of a complex relationship between the virus vine and vectors each component of which is interdependent on the other two The review suggests that a full understanding of the disease will require research and operational input from plant virologists entomologists vine physiologists pest controllers vineyard managers grapevine breeders/improvers and winemakers Such a wide range of expertise should ensure that the factors behind the spread of the disease over time (its epidemiology) are accurately determined and that effective management solutions are delivered over the course of decades

Impacts of leafroll‐associated viruses (GLRaV‐1 and ‐3) on the physiology of the Portuguese grapevine cultivar ‘Touriga Nacional’ growing under field conditions

“…According to these authors, as alternative, the TP content was driving directly to St synthesis, thus resulting in lower SS/St ratio in GLRaV‐1&‐3(+) leaves. Hence, according to Martelli et al (), St accumulates in chloroplasts, causing brittleness and increased thickness of leaf blades (corroborated in this study by LMA determinations, Table ), as well as reduced supply of sugars to the berries and nutrition of the trunk and roots (Charles et al , ). These source–sink relationships can also be limited by the loss of soluble proteins (Table ), particularly in Calvin‐Benson cycle enzymes and sucrose phosphate synthase, as well as by a lower availability of inorganic phosphate ( P i ) (Table ) to allow stoichiometric changes between TP and P i from chloroplast to cytosol and vice versa (Chaumont et al , ).…”

“…Relatively to leaf carbohydrate content, while SS concentration remains lower in the infected leaves, St concentration increased. This may be related to disturbance in the capacity to produce and to mobilise triose phosphates (TP) from stroma to cytosol and with obliterated and crushed sieve elements in the vascular bundles of leaves (Martelli et al , ; Charles et al , ), which impair SS translocation from foliar parenchyma, and/or with few sink fruits (Table ) for assimilated carbon (Chaumont et al , ). According to these authors, as alternative, the TP content was driving directly to St synthesis, thus resulting in lower SS/St ratio in GLRaV‐1&‐3(+) leaves.…”

“…In some varieties and regions leafroll‐associated virus 1 (GLRaV‐1) is also frequently detected (Santos et al , ). Both viruses, GLRaV‐1 and ‐3 (GLRaV‐1&‐3), are transmitted either by grafting or by mealybugs producing as characteristic symptom the inward rolling of leaves in late summer (Cabaleiro & Segura, ; Charles et al , ). Additionally, the mature leaves near the basal part of the shoots can acquire prematurely a red and reddish‐purple colouration in the interveinal areas, the leaf blade becomes thick and brittle, and sometimes they can produce necrotic spots on the upper side, resembling the symptoms of potassium deficiency (Charles et al , ; Naidu et al , ).…”

“…Both viruses, GLRaV‐1 and ‐3 (GLRaV‐1&‐3), are transmitted either by grafting or by mealybugs producing as characteristic symptom the inward rolling of leaves in late summer (Cabaleiro & Segura, ; Charles et al , ). Additionally, the mature leaves near the basal part of the shoots can acquire prematurely a red and reddish‐purple colouration in the interveinal areas, the leaf blade becomes thick and brittle, and sometimes they can produce necrotic spots on the upper side, resembling the symptoms of potassium deficiency (Charles et al , ; Naidu et al , ). Depending on the strain, grapevine cultivar and environmental conditions, leafroll virus infections can negatively influence the yield, sugar content and acidity of the must, berry skin phenolic content, resistance to biotic and abiotic stress and length of growing cycle and the vigour (Guidoni et al , ; Cabaleiro et al , ).…”

DNA markers to disentangle complexes of cryptic taxa in mealybugs (Hemiptera: Pseudococcidae)

“…Mealybugs (Hemiptera: Pseudococcidae) are major pests infesting a wide range of crops and ornamental plants worldwide (Ben-Dov 1994;Miller and Rossman 1995;Abate et al 2000;Millar 2002;Miller et al 2002Miller et al , 2005. These sap-sucking insects have been studied intensively for decades because of the economic losses they cause to agriculture, through direct damages to crops, virus transmission and decreases in yield quality (Sforza et al 2003;Charles et al 2006;Kuniyuki et al 2006;Douglas and Kruger 2008;Meyer et al 2008;Nakaune et al 2008).…”