Abstract
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.
Highlights
Viruses of the family Geminiviridae are phytopthathogens with circular, single-stranded DNA genomes encapsidated within characteristic twinned quasi-icosahedral particles
Leaves of squash plants showing symptoms typical of begomovirus infection were collected from the Agricultural Experimental Station (Sultan Qaboos University, Oman)
Oman and Iran have high levels of sequence identity and are distinct from the sequences of the other isolates. These findings strongly suggest that Watermelon chlorotic stunt virus (WmCSV) present in Oman was introduced from Iran
Summary
Viruses of the family Geminiviridae are phytopthathogens with circular, single-stranded (ss) DNA genomes encapsidated within characteristic twinned quasi-icosahedral particles. Geminiviruses have been divided into four genera (Begomovirus, Mastrevirus, Curtovirus and Topocuvirus) based on their genome organization, host range and insect vector [1]. The DNA A component of Old World begomoviruses encodes six genes; two in the virion-sense (AV1 and AV2) and four in the complementary-sense (AC1, AC2, AC3 and AC4) [6]. The DNA B component of bipartite begomoviruses encompasses one complementary-sense gene (BC1) that encodes movement protein (MP), and one virion-sense gene (BV1) encoding the nuclear shuttle protein (NSP) [6]. The host range of the virus extends to most cucurbits including melons, cucumber, pumpkin and squash Experimental plants such as Nicotiana benthamiana and N. glutinosa have been found to be hosts [14].
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