Molecular detection and characterisation of bipartite Begomoviruses associated with cucurbitaceous vegetables in Sri Lanka

Begomovirus infection is one of the major problems associated with cucurbit cultivation in Sri Lanka. A study was conducted to detect bipartite begomoviruses associated with cucurbits in the country. Cucumber, gherkin, pumpkin, bitter gourd, ridge gourd and snake gourd samples showing viral like symptoms of leaf mosaic, upward leaf curling, stunting, rosetting, puckering and fruit malformation were found to be infected with begomovirus. However, only cucumber and gherkin samples were detected to be infected with bipartite begomoviruses with both A and B genomes. All the other samples were detected as infected with monopartite begomoviruses with A genome. The sequence comparison of the coat protein gene of DNA-A in bipartite begomovirus associated with cucumber and gherkin showed a 97 % nucleotide identity with the Tomato Leaf Curl New Delhi Virus (ToLCND) (KP868764). The phylogenetic analysis of the cucumber isolate was distinct from all the other viruses; however clustered with different ToLCND viruses. DNA-B showed 90 % identity with the Bhendi Yellow Vein Mosaic Virus (BYVMV) (JQ359517). This new isolate was named as Tomato Leaf Curl New Delhi Virus-Cucumber [Sri Lanka: 2014]. This is the first known bipartite begomovirus associated with cucurbits in Sri Lanka.