Molecular characterization of a new species of begomovirus associated with yellow vein mosaic of bhendi (Okra) in Bhubhaneswar, India

Abstract

Yellow vein mosaic disease of okra is major constraint for the production of okra in India. It is caused by whitefly transmitted begomoviruses and results in severe economic losses of the crop. In the present study a new begomovirus (OYBHU isolate) infecting okra showing yellow vein symptoms from Bhubhaneswar, India was characterized. The complete genome sequence (homologous to DNA-A) was determined and it comprised 2757 nucleotides. Attempts to amplify DNA- B were not successful. However, the association of a betasatellite suggests that the isolate is monopartite and typical of the begomoviruses infecting malvaceous hosts in the Old World. The genome organization is characteristic of begomoviruses, encoding seven ORFs with two ORFs [AV1 (CP) and AV2] in virion sense strand and five ORFs (AC1-AC5) in complementary strand. Comparisons of the virus genome sequence with other known begomoviruses suggests that OYBHU virus isolate is distinct, with Croton yellow vein mosaic virus being its nearest relative, sharing the 81.4 to 86.1 % sequence identity. This is further supported by phylogenetic analyses with clustering of BYVBV on a well supported branch separated from all other begomoviruses. The name Bhendi yellow vein Bhubhaneswar virus (BYVBV) is proposed for virus isolate OYBHU with the additional descriptor [India: Bhubhaneswar:OYBHU:06]. Recombination analyses with BYVBV suggest that it is a recombinant and may have originated by the exchange of genomic segments between the begomoviruses Croton yellow vein mosaic virus, Bhendi yellow vein mosaic virus, Cotton leaf curl multan virus and Mesta yellow vein mosaic virus.