Location: Floral and Nursery Plants Research Unit
Title: Detection and molecular characterizations of new and emerging potyviruses of ornamental plants Authors
Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 9, 2009
Publication Date: August 12, 2011
Citation: Jordan, R.L., Guaragna, M.A., Putnam, M. 2011. Detection and molecular characterizations of new and emerging potyviruses of ornamental plants. Acta Horticulturae. 901:159-166. Technical Abstract: Floral crop sales comprise one of the fastest growing segments of US agriculture, forming an over $5.4 billion industry. Many plant virus diseases cause significant losses in the production and quality of ornamental crops, are very difficult to control, and new diseases occur as different crops are introduced or grown in new areas. Many crops are susceptible to multiple viruses, each of which may cause serious economic losses, and infected plant material may not be acceptable for export. Growers have reported problems with previously unreported viruses in several economically important ornamental crop species exhibiting virus-like symptoms. Testing of various ornamental plants exhibiting mosaic, ringspot, or flower break symptoms with our potyviral broad-spectrum monoclonal antibody PTY-1 revealed that the causal agent might be a potyvirus. Electron microscopic examination of leaf dips or thin sections usually revealed the presence of potyvirus-like particles or potyviral cytopathology, respectively. However, PTY-1 reactivity nor the presence of virions allows specific identification of the virus; the potyvirus group contains over 200 definitive and possible members which cause significant losses in many important agronomical and horticultural important crop species. Here we report the detection, cloning, sequencing and identity of potyviruses detected by PTY-1 in various ornamental plants. Total RNA extracts from symptomatic PTY-1 ‘positive’ plants were used with potyvirus-specific primers in RT-PCR assays. The degenerate primers for the genus Potyvirus direct the amplification of ca. 1600bp fragments from the 3' terminus of most potyviruses (including the coat protein gene and 3' NCR). PTY-1 immunocaptured (IC) virions were also used in IC-RT-PCR reactions. The resultant PCR amplicons were cloned, sequenced and compared to potyvirus sequences in the international databases. Serological and pairwise and phylogenetic sequence analysis revealed the identification of new potyviruses, including Tricyrtis virus Y in toad lily Tricyrtis formosana (in a mixed infection with Lily virus X potexvirus) and Omphalodes virus Y in Navelwort Omphalodes. Previously identified reoccurring potyviruses infecting Euphorbia (Euphorbia ringspot virus), Brugmansia (Columbian datura virus), Impatiens (Impatiens flower break virus), Osteospermum (Lettuce mosaic virus), and Schizostylis (Bean yellow mosaic virus) were also detected and confirmed.