Occurrence of Cymbidium mosaic and Odontoglossum ringspot viruses in orchid germplasm of Sikkim and Darjeeling hills, their identification and diagnosis

Abstract

Survey was conducted in Sikkim and Darjeeling hills for orchid viruses during 2007-08. Samples showing different kind of symptoms were collected and maintained in polyhouse at National Research Centre for Orchids, Pakyong, Sikkim.Electron microscopy of negatively stained preparations showed both Cymbidium mosaic (CymMV) and Odontoglossumringspot (ORSV) viruses from different species. Viruses from EM and ELISA positive samples were mechanically transmitted tovarious herbaceous hosts. CymMV was successfully transmitted to Datura stramonium and Chenopodium amaranticolor.However, ORSV was mechanically transmitted to Nicotiana benthamiana and Gomphrena globosa. EM and ELISA resultsrevealed that CymMV and ORSV were commonly found in mixed infections causing severe damage to host plants. Both theviruses are highly contagious, stable, found in very high concentration in host tissue and being spread mainly by contaminated tools.