|Kousik, Chandrasekar - Shaker|
Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2008
Publication Date: 7/1/2008
Citation: Adkins, S.T., Li, W., Hilf, M.E., Turechek, W., Kousik, C.S., Baker, C., Webb, S.E. 2008. Identification of plant reservoirs and genome characterization of Squash vein yellowing virus, causal agent of viral watermelon vine decline in Florida. Phytopathology. 98(6):S10
Technical Abstract: Squash vein yellowing virus (SqVYV) was identified in cucurbits in Florida in 2005 and shown to be whitefly-transmissible and to induce a previously observed watermelon vine decline and fruit rind necrosis. Only cucurbits have been determined to be hosts for SqVYV so common cucurbit weeds in south Florida were examined as potential reservoirs of SqVYV. Over 40% of 86 balsam-apple (Momordica charantia) plants collected from watermelon growing areas with previously reported cases of vine decline were found to be infected with SqVYV. Creeping cucumber (Melothria pendula) was determined to be an experimental host for SqVYV. Collectively, these results demonstrate that cucurbit weeds can provide reservoirs for SqVYV in Florida. Sequencing of the SqVYV genomic RNA showed one large open reading frame encoding a single polyprotein, a typical genome organization for most members of the family Potyviridae. Phylogenetic analysis of the ten mature proteins predicted to be derived from the SqVYV polyprotein supports classification of SqVYV as a novel species within the genus Ipomovirus. The presence of P1a and P1b proteins, and the absence of an HC-Pro protein, makes the genome organization of SqVYV similar to Cucumber vein yellowing virus but different from Sweet potato mild mottle virus, both recognized members of the genus Ipomovirus. This indicates that the taxonomy of the genus Ipomovirus needs to be re-examined and a new genus created within the family Potyviridae to accommodate the observed discrepancies in ipomovirus genome organization.