Unit of Plant Virology, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi-110012.
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.
Spotted wilt is becoming a potential threat to tomato (Lycopersicon esculentum Mill) cultivation in the Indian subcontinent. The disease incidence is more in kharif and summer seasons as compared to rabi season. Field symptoms of the disease include extensive necrosis of the buds and petioles, necrotic spots on leaves and concentric rings on fruits. Necrosis affected tomato samples collected from farmers fields from Coimbatore (Tamil Nadu), Kanpur (Uttar Pradesh) and Pune (Maharashtra) were subjected to biological and molecular assays. The virus from the field collected samples was easily mechanically transmitted to cowpea cv. Pusa Komal. Both localized as well as systemic infections characterized by chlorotic/necrotic lesions, veinal and systemic necrosis were observed. Extracts from leaves and fruits from the field samples reacted with polyclonal antiserum directed against nucleocapsid protein (NP) of Groundnut bud necrosis virus (GBNV) in direct antigen-coated enzyme-linked immunosorbent assay. Symptomatic samples were subjected to reverse transcriptase polymerase chain reaction to identify the virus. Using the primer pair HRP26 5’ATGTCTAACGTYAAGCARCTG 3′) and HRP28 (3’TTACAATTCCAGCGAA GGACC 5′), the NP gene of the tomato tospovirus isolates originating from three locations were amplified, cloned and sequenced (GenBank Accession numbers AY463968-TN, AY734235UP, and AY727923-MH). The NP gene was of similar size, 831 nucleotides encoding protein of 276 amino acids. The NP gene of the tomato tospovirus isolates shared 99–100% amino acid sequence identity with GBNV (type isolate), suggesting the association of GBNV with spotted wilt disease. Comparative sequence analysis revealed that the NP gene among GBNV isolates from tomato from five different locations (Karnataka, Kerala, Maharashtra, Tamil Nadu and Uttar Pradesh) was highly conserved (95–100%), suggesting their common origin.
