Impact of Cymbidium mosaic virus on Native and Cultivated Orchids in Western Ghat - Kerala.

Abstract

Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV) are two major orchid viruses detected in native and imported orchid plants of India. These viruses are growth debilitating with high stability and high spread rates. A survey was conducted in eight districts of Kerala for detecting the prevalence of CymMV and ORSV in native and cultivated orchid plants. DAC- ELISA technique using specific antibodies for CymMV and ORSV was used to detect viruses in collected orchid samples. The presence of CymMV was detected in all orchid nurseries surveyed, and the incidence varied from five to 100% in different areas. The coat protein of the CymMV strain was cloned and sequenced and its similar sequences were observed against the available database, and it was found to be more related to foreign strains. It was confirmed that the plants acquired the infection either during importation or later during close maintenance in the nurseries post-importation. Whereas the wild population of orchids surveyed from the Western Ghat of Kerala, did not test positive for CymMV, they were able to take up the infection upon artificial inoculation. CymMV is highly contagious and can easily transmit through infected plant sap, there is a greater possibility of spread of this virus to other orchids when kept in its vicinity. Even though CymMV was not a quarantined pathogen, there are possibilities of its spread to the native wild orchid population, and it may have unfavourable results, especially in the biodiversity hotspots like the Western Ghats of Kerala.