Co-Authors:
Cohen, J., Dept. of Virology, ARO, Volcani Center, Bet Dagan 50250, Israel
Rosner, A., Dept. of Virology, ARO, Volcani Center, Bet Dagan 50250, Israel
Kagan, S., Dept. of Ornamental Hort., ARO, Volcani Center, Bet Dagan 50250, Israel
Lampel, M., Dept. of Virology, ARO, Volcani Center, Bet Dagan 50250, Israel
Beckelman, H., Dept. of Virology, ARO, Volcani Center, Bet Dagan 50250, Israel
Maslenin, L., Dept. of Virology, ARO, Volcani Center, Bet Dagan 50250, Israel
Zeidan, M., PPIS Ministry of Agriculture, Bet Dagan 50250, Israel
Gera, A., Dept. of Virology, ARO, Volcani Center, Bet Dagan 50250, Israel
Abstract:
Tabernamontana divaricata, a member of the family Apocynaceae, is an evergreen shrub native to tropical areas of India and is widely grown around the world for its ornamental value. The plant was introduced into Israel in 1986 and is cultivated as a pot plant which blooms all the year round. During August 1999, specimens of T. divaricata cv. "Flore Pleno" exhibiting a range of symptoms were collected from a commercial nursery. The symptoms varied widely and included chlorotic ringspots, chlorotic banding, oak-leaf patterns and mosaic. At the end of the winter, after the cold season, large yellow spots which later became necrotic appeared on fully expanded leaves. The necrotic zone later fell out, leaving "shot holes". Leaf samples were analyzed by transmission electron microscopy (TEM) of leaf dip preparations. Typical tobamovirus-like particles were observed only in samples taken from visibly infected plants. Crude sap from infected tissue was mechanically transmitted to various test plants, which developed symptoms characteristic of tobamovirus infection. No symptoms were observed in mechanically inoculated Lycopersicon esculentum (tomato) or Ocimum basilicum (basil). The virus was purified from mechanically infected Nicotiana tabaccum cv. Samsun and identified as Tobacco mild green mosaic virus (TMGMV). Purified preparations contained numerous rigid rod-shaped particles similar to those observed in crude extracts of infected leaves. ELISA detected the virus in leaves which displayed symptoms, including the green areas surrounding yellow and necrotic spots. Particles from crude plant extracts had a normal length of 300 nm. The 5′ - terminus of the viral RNA was cloned and sequenced, and comparison of the predicted amino acid sequence with those of other tobamoviruses revealed 93% identity with the TMGMV genome, thus confirming TMGMV infection of Tabernamontana.
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