The quantity and genetic diversity analysis of Grapevine vein clearing virus in four types of grapevine tissues
S. HONESTY (1), Q. Guo (2). (1) Missouri State University, Hazelwood, MO, U.S.A.; (2) Missouri State University, Mountain Grove, MO, U.S.A.
<i>Grapevine vein clearing virus</i> (GVCV) is the first DNA virus discovered in grapevine and closely associated with a vein-clearing and vine decline disease in the Midwest region of the United States. Its genome of 7,753 bp contains three open reading frames (ORFs). ORF3 is predicted to encode domains of Zinc Finger (ZF), Reverse Transcriptase (RT) and RNase H. In this study, qPCR was conducted to measure the copy number of GVCV in young leaf, fully expanded leaf, stem phloem tissue and root tip of three individual grapevines that were infected with the GVCV type isolate. A grapevine <i>β-actin</i> gene was also quantified to calibrate the copy number of GVCV in these four tissues. As a result, GVCV has an average of 4.6 copy/actin in young leaf, 3.7 in fully expanded leaf, 14.4 in phloem, and 0.5 in root tip, respectively. Statistic analysis of GVCV copy number per <i>β-actin</i> indicated that the quantity of GVCV in the root tip is significantly different from that of GVCV in the other three tissues. A genetic diversity study has also been performed within the ZF and RT region of GVCV variants from the four tissue types. It was found that the tissue type did not impact the genetic diversity of the GVCV ZF and RT region.
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