Indian Journal of Virology

Tobacco streak virus (TSV) a new virus from India causing sunflower necrosis and peanut stem necrosis disease in sunflower and peanut crops respectively. TSV is widely prevalent and continued to be a major constraint in sunflower and peanut crops since 1997 from Maharashtra, Karnataka, Andhra Pradesh and Tamil Nadu. In recent years an extensive survey has been condeucted in the major sunflwoer growing regions of the country and observed that the virus is confined to main kharif season of sunflower and peanut crops with the disease incidence upto 90 per cent. In addition to sunflower and peanut crops, the virus also kown to infect number of economically important crops and weeds under natural conditions. In the present study, over 200 suspected field infected TSV isolates wee collected and diagnosed by Direct Antigen Coating ELISA using virus specific polyclonal antibodies. Further, in order to establish the sequence diversity among the crops and weeds, the representative isolates were characterized molecularly, especially the TSV-CP gene from the RNA 3 component. Cloned and sequenced nearly thirty TSV isolates collected from sunflower, peanut, cotton, okra, jute, parthenium and xanthium. The TSV-CP gene has 717 bp in size and encodes for 238 amino acids. The TSV-CP nucleotide sequence analysis showed 99.0 to 100 per cent identity among the Indian isolates and 88.0 per cent identity with the reference TSV isolate from Wisconsin, USA. Biological and molecular studies showed that, the TSV is known to infect economically important crop plants in India and it has been shown that the TSV coat protein gene is highly conserved among the crop plants and weeds. The possible spread of this virus in other economically important crops needs to be closely monitored.