Date of Graduation

Summer 2015

Degree

Master of Science in Plant Science (Agriculture)

Department

College of Agriculture

Committee Chair

Wenping Qiu

Keywords

badnavirus, grapevine, phylogenetic analysis, Grapevine vein clearing virus, open reading frame II, CHA, VRU, Vitis

Subject Categories

Plant Sciences

Abstract

Grapevine vein clearing virus (GVCV) associated disease poses a threat to the grape production in the Midwest region of the United States. Two isolates, GVCV-CHA and GVCV-VRU1, have been identified in a grape cultivar ‘Chardonnay' and a wild Vitis rupestris, respectively. The most variable Open Reading Frame II regions share 83.3% identity at nucleotide levels with a characteristic 9 bp insert in GVCV-VRU1. To investigate the genetic diversity of GVCV, I cloned and sequenced the ORFII regions of GVCV isolates that were collected from grapevines in commercial vineyards and native habitats. Studies found that the ORFII of a GVCV isolate from grape cultivar ‘Chardonel' shared 88.5% nucleotide identity with that of GVCV-VRU1 and contained the 9 bp insert. The ORFII of a GVCV isolate, GVCV-VRU2, from another wild V. rupestris accession does not contain the 9 bp insert and only shared 88.4% identity with both GVCV-VRU1 and GVCV-CHA. Sequencing of the entire genome shows a 91.6% and 93.4% identity with GVCV-CHA and GVCV-VRU1 respectively. Furthermore, minor changes of ORFII were found after GVCV-CHA was grafted onto different grape varieties. These results suggest that GVCV is present as genetically complex populations in cultivated and wild grapevines. The complexity of GVCV populations and the discovery of a new isolate implies dynamic evolution of GVCV and imposes a challenge of managing GVCV-associated disease.

Copyright

© Steven Joel Beach

Campus Only

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