Watermelon chlorotic stunt virus (WmCSV) is a bipartite begomovirus (genus Begomovirus, family Geminiviridae) that causes economic losses to cucurbits, particularly watermelon, across the Middle East and North Africa. Recently squash (Cucurbita moschata) grown in an experimental field in Oman was found to display symptoms such as leaf curling, yellowing and stunting, typical of a begomovirus infection. Sequence analysis of the virus isolated from squash showed 97.6-99.9% nucleotide sequence identity to previously described WmCSV isolates for the DNA A component and 93-98% identity for the DNA B component. Agrobacterium-mediated inoculation to Nicotiana benthamiana resulted in the development of symptoms fifteen days post inoculation. This is the first bipartite begomovirus identified in Oman. Overall the Oman isolate showed the highest levels of sequence identity to a WmCSV isolate originating from Iran, which was confirmed by phylogenetic analysis. This suggests that WmCSV present in Oman has been introduced from Iran. The significance of this finding is discussed.
Keywords: Begomovirus; Oman; WmCSV; squash.