Department of Plant Pathology, Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore-641003, India.
Abstracts of the papers presented at the 16th Annual Convention and International Symposium of Indian Virological Society on “Management of Vector-Borne Viruses” at International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru-502324, Hyderabad, India, February 7–10, 2006.
Blackgram (Vigna mungo) belonging to the family Fabaceae is an important pulse crop in India, Nepal, Bangaladesh and Myanmar. A new stem necrosis disease was observed during kharif, 2002 in most of the urdbean cultivated areas of Tamil Nadu. The diseased plants exhibited brown necrotic areas in the leaves, petiole, necrosis of stem and drying of the plants from the tip and finally death of the entire plant. Mechanical inoculation of the infected samples of urdbean on 6 day-old cowpea (cv 152) plants showed brown and chlrotic rings. In Nicotiana tabaccum, it produced ring spots similar to that exhibited by ilarvirus group. The purified preparations of the virus through electron microscope showed isometric particles. The ultraviolet absorbance of the purified virus was measured and the ratio of A260/A280was determined as 1.41. ELISA tests of naturally -infected samples and sap-inoculated plants showed positive reaction to antibodies of TSV. The virus was not transmitted through seeds. RT-PCR tests of tissue from diseased blackgram plants using primer specific for the coat protein gene of TSV resulted in an amplicon size of approximately 700 bp and the coat protein gene was cloned and sequenced (Genbank DQ 225172). The sequence analysis showed 99 per cent similarity with the TSV coat protein of cotton. On the basis of host range, serological relationship, electron microscopy, and sequence analysis of the CP region, the virus was identified as a strain of TSV.
