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The first report of Cymbidium mosaic virus (CymMV) in orchids from India

A.R. Sherpa1, V. Hallan1, R. Ram1, S.P Vij2, P. Pathak2, I.D. Garg3 and A.A.Zaidi1*

1 Virology Lab, Floriculture Division, Institute of Himalayan Bioresource Technology, (CSIR), P.O. box 6, Palampur-176061 (HP)
2 Department of Botany, Panjab University, Chandigarh-160 014
3 CPRI, Shimla (HP), India.

*zaidi_aijaz@yahoo.com

Accepted for publication 10/03/03

A survey of orchids from various Indian provinces, identified a variety of different species including Cymbidium aloifolium, Cymbidium Hybrid (Arabian Sea), C. ividioides, Epidendrum sp, Liparis botanensis, Phaius tankervilleae and Pholidota imbricate, which showed virus-like symptoms including flower colour break, leaf necrosis and necrotic spotting (Fig.1).


Fig. 1. Symptomatic Plant (Phaius tankervilleae)
showing necrotic lesions (inset, enlarged leaf part)

These symptoms were similar to those reported earlier for CymMV (Zettler et al., 1990). Sap from these plants was inoculated onto Datura stramonium and Chenopodium murale, inducing blotchy local lesions which varied with plant species, season and environmental conditions. CymMV was detected in these indicators and the symptomatic orchids using a polyclonal DAS-ELISA kit (Agdia, USA). When examined by transmission electron microscopy, partially purified virus preparations showed the presence of 440-480 nm flexuous particles, which showed enhanced trapping (Fig. 2) and clumping (Fig. 3) with CymMV antiserum (obtained from Dr. Z. Maat, The Netherlands) in immuno-electron microscopy.


Fig. 2 Electron micrograph of partially purified CymMV (at 81,000 times magnification)


Fig. 3. Electron micrograph of partially purified CymMV, trapped and decorated with CymMV polyclonal antiserum (at 81,000 times magnification)


Figure 4 .1% Agarose Gel Electrophoresis of RT-PCR amplified product of CymMV, Lane 1, 100 bp DNA ladder, lane 2 & lane 3 534 bp CymMV

RT–PCR was performed using the primer pair UI and LI (Seoh et al., 1998) and a product of expected size (~534 bp) was amplified (Fig. 4). This product was cloned and sequenced and was found to share 94% sequence homology with the 5' end of the RdRp gene of Korean type 2 isolate of CymMV (Accession No. AF016914). This is the first definitive report of CymMV infecting orchids in India.

References

Seoh ML, Wong SM, Zhang L, 1998. Simultaneous TD/RT-PCR detection of Cymbidium mosaic potexvirus and Odontoglossum ringspot tobamovirus with a single pair of primers. Journal of Virological Methods 72, 197-204.

Zettler FW, Ko NJ, Wisler GC, Chang CG, Elliot MS, Wong SM, 1990.Viruses of orchids and their control. Plant Disease 74, 621-626.

The British Society for Plant Pathology