These plants were subsequently vegetatively propagated in our greenhouse at the University of California, Berkeley, and an isolate found in a symptomatic Merlot plant from Rutherford, California was selected to be fully sequenced. The overall genomic diversity amongst GLRaV-3 had remained fairly limited until the recent publication of a South African isolate (GH11), which had ~68% nucleotide identity with other GLRaV-3 variants, but showed higher identity to a partial sequence of GLRaV-3 from New Zealand (NZ-1).Дuring a recent survey of vineyards in Napa Valley, California USA, we found plants with divergent partial genome sequences of GLRaV-3, with close homology to NZ-1 (GLRaV-3e cluster). Two distinct isolates, GP18 and WA-MR, have become representative of two major clades of GLRaV-3, but more intensive sampling revealed many genetically separated well-supported clades, potentially leading to seven subclades within GLRaV-3. Grapevine leafroll-associated virus 3 (GLRaV-3) is the type species of the genus Ampelovirus. In fact, Closteroviridae recently underwent a taxonomic revision, and it is anticipated that the number of tentative GLRaV species will be reduced to five.

An additional GLRD-causing virus, Grapevine leafroll-associated virus 7, is still unclassified, although a recent proposal will place it in a new genus. The mealybug-transmitted viruses are in the genus Ampelovirus, and Grapevine leafroll-associated virus 2, which has no known vector, is in the genus Closterovirus. All GLRD-causing viruses are phloem-limited and infect Vitis hosts.

GLRD is caused by several related positive single-stranded RNA virus species in the family Closteroviridae, which contains the largest known plant RNA virus genomes. Besides leaf rolling, other GLRD symptoms include abnormal pigmentation of the leaf interveinal area, disruption of the phloem and delayed grape maturation. Grapevine leafroll disease (GLRD) is observed in all wine-making regions worldwide, limiting grape production by up to 40 percent.

Macvector reverse alignment