Grapevine vein clearing virus: a new virus of grapevine
Grapevine vein clearing virus (GVCV) is a new badnavirus that is closely associated with an emerging disease of grapevine (Vitis vinifera) in the Midwest region of the USA. This disease has been observed for several decades in vineyards, but symptoms have probably been attributed to Grapevine fanleaf virus, thus delaying the identification of a new virus. In early spring, infected vines show a narrow strip of chlorotic tissues along the major and minor veins of fully expanded leaves of young shoots. Chlorotic veins are translucent when symptomatic leaves are held against sunlight (a characteristic symptom of the disease). Young shoots have short internodes with zigzag growth. Mature leaves are of reduced size, deformed, and display various patterns of chlorotic to yellowish tissues, as well as rolled margins. In advanced stages of infection the vines become dwarfed, bear fewer bunches and may show decline symptoms. GVCV has been detected in several grapevine cultivars (e.g. Cabernet franc, Cabernet sauvignon, Cayuga white, Chardonel, Chardonnay, Corot noir, Merlot, Muscat, Riesling, Traminette, Valvin, Vidal blanc, Zinfandel), as well as in a few plants of wild Vitis spp. growing near commercial vineyards. According to preliminary experiments, the cultivar ‘Chambourcin’ seems to be resistant. GVCV is a graft-transmitted virus, and it is assumed that the propagation of infected material is the main pathway for spreading the disease. The fact that the disease has been frequently observed in Midwest vineyards in recent years, may suggest that GVCV is slowly spread from vine to vine by arthropod vectors. Although, no vector has been identified for the moment, it can be recalled that some badnavirus are transmitted by pseudococcid mealybugs. Further studies are needed to better understand the biology, epidemiology, geographical distribution and economic impact of GVCV.
Sources
Guo Q, Honesty S, Xu ML, Zhang Y, Schoelz J, Qiu WP (2014) Genetic diversity and tissue and host specificity of Grapevine vein clearing virus. Phytopathology 104(5), 539-547.
INTERNET
National Clean Plant Network. Grapevine Vein Clearing and Vine Decline Disease. http://ucanr.edu/sites/NCPNGrapes/files/171630.pdf
Zhang Y, Singh K, Kaur R, Qiu WP (2011) Association of a novel DNA virus with the grapevine vein-clearing and vine decline syndrome. Phytopathology 101(9), 1081-1090.