Yellow vein mosaic disease is the major biotic constraint of okra cultivation in Sri Lanka. Identification and detailed molecular characterization of associated pathogen is needed for effective disease management. The genome of the begomovirus and betasatellite were amplified in symptomatic plant samples using specific degenerate primers. DNA-A genome of twelve isolates representing different locations in Sri Lanka were cloned, sequenced and deposited in GenBank database (Accession No- KX698087- KX698092 and MH455207- MH455212). Size of the complete nucleotide sequences ranged from 2735 to 2786 bp. The genome organization showed characteristics of begomoviruses. The pairwise sequence identity revealed the association of two different begomovirus species. Five of the isolates showed > 91% of sequences identity with Bhendi yellow vein mosaic virus, and the rest of the seven isolates were around 92% of identity with Okra enation leaf curl virus. This is further supported by phylogenetic analysis where both of these group of isolates were in different cluster. Recombination analysis showed the presence of recombinant fragments in the virus isolates associated with okra yellow vein mosaic disease (OYVMD) in Sri Lanka. Attempts to amplify DNA- B were failed in any of the samples tested. However, both type of the begomovirus species associated with betasatellite species, Bhendi yellow vein mosaic betasatellite. The present study has revealed the association of two distinct monopartite begomovirus species, Bhendi yellow vein mosaic virus or Okra enation leaf curl virus, with OYVMD in Sri Lanka.
Keywords: Begomoviruses; Betasatellites; Okra; Okra yellow vein mosaic disease; Phylogenetic relationship.