ISHS Acta Horticulturae 568: X International Symposium on Virus Diseases of Ornamental Plants
DETECTION AND FIRST REPORT OF DASHEEN MOSAIC VIRUS AND A SECOND POTYVIRUS INFECTING THE TERRESTRIAL ORCHID SPIRANTHES CERNUA |
| Authors: | R. Jordan, M.A. Guaragna, G. Kinard, S. Lynn |
| Keywords: | orchid, potyvirus, PCR, monoclonal antibody |
| Abstract:
>Spiranthes cernua is a terrestrial orchid that grows in moist areas in the southeastern U.S. Cultivated varieties are now also being used as flowering perennials. A commercial grower in West Virginia observed chlorotic blotching and/or mosaic symptoms on the leaves of Spiranthes cernua ‘Chadds Ford’ and sent asymptomatic and symptomatic plants to us for diagnosis. Particles of the size and shape consistent with potyviruses were observed in preparations from symptomatic leaf tissue and no other types of virions were readily observed. The symptomatic Spiranthes was analyzed by ELISA using our panel of potyvirus specific monoclonal antibodies (McAbs). The original symptomatic samples reacted with PTY 1, an antibody specific for a highly conserved site in the potyviral coat protein. Total nucleic acid extracts from infected Spiranthes were used as templates for reverse transcriptase polymerase chain reaction (RT-PCR) with two different sets of potyvirus-specific primers which amplify highly conserved 335 bp and ~700 bp fragments from the carboxy-terminus of the coat protein gene and 3’ non-coding region of most potyviruses. The PCR fragments amplified from one of the Spiranthes plants were subsequently cloned and sequenced. Amino acid comparisons to the corresponding segments of other potyviruses revealed identity to Dasheen mosaic virus (DsMV). Serological relatedness to DsMV was confirmed using DsMV-specific polyclonal antisera in both ELISA and tissue print assays. Some asymptomatic plants however were PTY 1 McAb positive and DsMV polyclonal Ab negative, suggesting the possible presence of an additional potyvirus in these samples. This is believed to be the first report of any virus infection in the genus Spiranthes and the first report of Dasheen mosaic virus infecting a member of the Orchidaceae. | |
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