Department of Plant Pathology, Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore-641003.
Abstracts of Research Papers Presented during the National Symposium of Indian Virological Society at Unit of Plant Virology, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi-110 012, October 14–1.
Cowpea (Vigna unguiculata (L.) Walp., Family: Fabaceae), popularly known as poor man's pulse crop, is severely affected by number of viral diseases. Recently, natural incidence of bud blighting and necrosis of entire plants was noticed in the cowpea fields of Tamil Nadu Agricultural University. Survey conducted in the fields revealed the occurrence of disease incidence to the maximum of 23% in variety CO711. Inoculated cowpea plants (COCP7) showed chlorotic and necrotic spots under glasshouse conditions. In host range studies, the cowpea virus was successfully transmitted to cotton, sunflower, cucurbits, bhendi and saranai. The dilution end point of the virus was found to be between 10−4 and 10−5. The virus was inactivated at a temperature between 55°C and 60°C. The virus remained infective up to 48h at 4°C. Electron microscopic observation of infected leaf dip preparation revealed isometric particles to the size of 35 nm diameter. SDS-PAGE analysis of the purified virus preparation showed the presence of a major polypeptide with relative molecular mass (Mr) 29kDa. The virus was serologically related to ilarviruses of soybean, sunflower and strawberry. Using primers specific to the CP coding region of Tobacco streak virus (TSV) of sunflower, RT-PCR was successful in amplifying the cowpea ilarvirus CP gene. On the basis of symptomatology, biological studies, physical properties, particle morphology and molecular characterization the cowpea ilarvirus was identified as a strain of TSV
