Indian Phytopath. cbaZYXWVUTSRQPONMLKJIHGFEDCBA 55 (1) : 84 c86 (2002) Indexing of leaf and seed samples of tomato and bell pepper for tobamoviruses T.R. CHITRA, H.S. PRAKASH, S.E. ALBRECHTSEN*, H.S. SHETTY and S.B. MATHUR* Department of Studies in Applied Botany and Seed Pathology, University of Mysore, Manasagangotri, Mysore 570 006 Key words: ToMV, TMV, ELISA, indicator plant test, tomato, bell pepper Tomato (Lycopersicon esculentum Mill.) and bell pepper (Capsicum annuum L.) are the major commercial vegetable crops. Tomato mosaic tobamovirus (ToMV) and Tobacco mosaic tobamovirus (TMV) cause significant yield loss and reduce fruit quality in tomato and bell pepper (3,15,7). ToMV and TMV are extremely stable and easily transmitted mechanically from seeds to seedlings during transplantation (3,14). In India, incidence of TMV in tomato (13) and pepper (12) has been reported based on indicator plant test. Cherian and Muniyappa (5) indexed tomato seed samples for TMV by indicator plant (Nicotiana glutinosa) test and ELISA. So far occurrence of ToMV and TMV in commercial seed samples of tomato and bell pepper has not been reported. Further, the bell pepper fields are not indexed for the presence of TMV. This paper distinguishes the tobamoviruses infection in leaf and seed samples. Seed samples collected from seed companies were also indexed for ToMV/ TMV. Tomato and bell pepper crops were surveyed during 1993-1996 in Karnataka. 153 locations covering an area of 156 ha of tomato and 40 locations representing 19 ha of bell pepper were surveyed. For each field of one hectare, five randomly selected rows were counted for healthy *Danish Government Institute of Seed Pathology for Developing Countries, Thorvaldsensvej 57, DK-1871 Frederiksberg, Copenhagen, Denmark Fax: +91 821 411467; E-mail: legume@sancharnetin and diseased plants, and the per cent disease incidence was calculated based on the proportion of infected plants. Leaf and fruit samples were collected from infected plants. The seeds from tomato fruits were extracted after fermentation and dried under shade. Bell pepper fruits were cut longitudinally into two halves and the seeds were removed and air-dried in shade. Fifty-eight seed samples of tomato and four of bell pepper were also collected from seed companies (Karnataka State Seed Certification Agency, KSSCA) and other agencies. Tomato seed/leaf samples (each 0.3 g) were extracted in 3 ml of 0.05 M phosphate buffer (pH 7.2) using pestle and mortar. The samples of bell pepper were extracted in 0.03 M disodium hydro- gen phosphate containing sodium diethyl dithio- carbamate (3 ml) and activated charcoal (75 mg/ ml). The sap was applied to indicator plants. A local lesion host, N. glutinosa, for both TMV and ToMV and N. sylvestris and N. tabacum cv. White burley, which react with systemic infection to TMV, but with necrotic local lesion (NLL) to ToMV were used. Leaf and seed samples were also tested for ToMV/TMV by following the direct antigen coating ELISA (10). Seed/leaf samples (1/100, w/v) of tomato and bell pepper were extracted in antigen buffer. The extracts were allowed to react separately with polyclonal antisera to ToMV and TMV obtained from the Danish Government Institute of Seed Pathology for Developing Countries (DGISP).