Molecular identification and biological characterisation of a begomovirus associated with okra enation leaf curl disease in India

An unusual symptom was noted in okra originating from Haryana state (India) consisting of leaf curl associated with enations. These were distinct from the leaf curl and/or vein yellowing symptoms usually shown by okra. PCR-mediated amplification was used to show the presence of a begomovirus and the complete genome sequences were determined for seven isolates. The sequences showed high levels of nucleotide sequence identity (91.9–99.1 %). In comparison to begomovirus sequences available in the databases the okra sequences showed the highest levels of nucleotide sequence identity (84.5 to 87.1 %) with Mesta yellow vein mosaic virus (MeYVV) and thus were classified as belonging to a novel begomovirus species, tentatively named Okra enation leaf curl virus. In common with the majority of begomoviruses, Okra enation leaf curl virus (OELCuV) was shown to have a recombinant origin. Analysis of the transmission characteristics of a wild-type virus isolate by Bemisia tabaci showed the minimum acquisition access period to be 1 h and the minimum inoculation access period to be 30 min, with female insects transmitting with a greater efficiency than male insects. Under controlled conditions the host range of the virus was shown to be very narrow, limited to two species in the family Malvaceae, okra (Abelmoschus esculentus) and hollyhock (Althaea rosea), and seven in the family Solanaceae.