Molecular Identification of Potyviruses Infecting Bulbous Ornamentals by the Analysis of Coat Protein (CP) Sequences

Potyviruses (genus Potyvirus, family Potyviridae) are transmitted by aphids in a non-persistent manner and cause significant losses in many crops including bulbous ornamentals. Host range, symptoms, physical and biochemical properties of many potyviruses in bulbous ornamentals are reported, but, especially for viruses infecting ornamentals of minor economical importance, sequence data are still lacking. We used molecular techniques for the identification, characterization and detection of these viruses. Leaf material of several ornamental crops showing virus-like symptoms were tested in indirect ELISA, using monoclonal antibodies specific for potyviruses. Generic potyvirus primers were used in an RT-PCR to amplify the 3' terminal region of these viruses. The fragments encode the viral coat protein (CP) gene and comprise the 3'-untranslated region (3'-UTR). Nucleotide sequences of the obtained fragments were determined and compared with potyvirus sequences present in the NCBI database using the BLAST algorithm. We have characterized some potyviruses previously accepted by the International Committee on Taxonomy of Viruses (ICTV), including Freesia mosaic virus (FreMV), Gloriosa stripe mosaic virus (GSMV), Hippeastrum mosaic virus (HiMV), Hyacinth mosaic virus (HyaMV), Iris mild mosaic virus (IMMV) and Nerine yellow stripe virus (NeYSV). Additionally, the identities of other potyviruses infecting ornamentals such as Anemone, Galtonia, Muscari, Ornithogalum, Allium, Stenomesson and Veltheimia have been determined. These viruses, however, have not yet been reported by the ICTV. The virus-specific sequence information generated in this research project can subsequently be used to develop PCR-based detection methods.