Page 40 - Grapevine NovDec 2020
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Around The Vineyard
Around The Vineyard
Symptoms of Grapevine red blotch virus – note the red veins in the leaf
sified in three genera, Ampelovirus, Closterovirus, placed GRBV in a new genus, named Grablovirus,
and Velarivirus. Grapevine leafroll associated within the Geminiviridae family. As stated above,
virus -1, GLRaV-3, and GLRaV-4 belong to the it has been difficult to demonstrate Koch’s postu-
Ampelovirus genus. Grapevine leafroll associated lates, with grapevine-infecting viruses. There are
virus -2 is a Closterovirus and GLRaV-7 is a member many reasons for this. Firstly, there are no alter-
of the Velarivirus genus. Some researchers claim native hosts that are susceptible to most grapevine
that GLRaV-7 should not be considered a leafroll infecting viruses (some exceptions exists).
virus because it only produces mild symptoms in
grapevines. Further, recent research has shown Secondly and most important, grapevine viruses
that GLRaV-7 was isolated from a mixed leafroll cannot be mechanically transmitted onto grape-
infected vine and symptoms were due to the other vines. These viruses need to be introduced to a
leafroll virus present at the time. When found vine via grafting (graft-transmission) and/or need
alone GLRaV-7 does not appear to show typical lea- a biological vector for successful transmission. Dr.
froll symptoms. Marc Fuchs team at Cornell University was able to
demonstrate that GRBV genetic material is respon-
Grapevine red blotch virus (GRBV) is the second sible for red blotch foliar symptoms in red fruited
virus species discovered in grapevines that carries grapevine varieties. The work was done using
DNA instead of RNA as its genetic material. Both sophisticated recombinant DNA molecular tech-
its molecular and structural characterization has niques to introduce the virus genetic material into
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