Submitted to: Phytopathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/23/2005
Publication Date: 10/7/2005
Citation: Hammond, J., Reinsel, M.D., Maroon-Lango. 2006. Identification and full sequence of an isolate of Alternanthera mosaic potexvirus infecting Phlox stolonifera. Archives of Virology. 151:477-493. Interpretive Summary: Phlox plants with disease symptoms were identified at a commercial nursery by Pennsylvania Department of Agriculture inspectors, and the cause of the disease was determined to be an unidentified virus. Infected plants were transferred to the USDA-ARS Floral and Nursery Plants Research Unit, where the causal virus was isolated and characterized using a variety of methods including determination of host range, serological reaction with antisera specific for known viruses, and molecular cloning of the complete viral genome. The nucleic acid sequence of the virus was found to be almost identical to that of a virus named Alternanthera mosaic virus, previously reported only from a weed plant in Australia. The virus was also found to be related to Papaya mosaic virus, which has previously been found to infect several ornamental plants. The close relationship may have led to the prior mis-identification of the virus as Papaya mosaic virus. Similar isolates of Alternanthera mosaic virus were detected in other plants of creeping phlox, and trailing portulaca, from a Maryland nursery. Several other ornamental plants were found to be susceptible to the virus, suggesting that Alternanthera mosaic virus has the potential to spread to other ornamental crops. The ability to detect and identify the virus will allow growers to select uninfected propagating material in order to produce healthy plants.
Technical Abstract: A potexvirus infecting creeping phlox, Phlox stolonifera, was isolated from plants produced in a commercial nursery in Pennsylvania. Western blotting was used to show that the virus was serologically related to other potexviruses, including Papaya mosaic virus (PapMV), Clover yellow mosaic virus (CYMV), Plantain virus X (PlMV), Potato virus X (PVX), and Potato aucuba mosaic virus (PAMV). Of these, the phlox virus was most closely related to PapMV. Initial sequencing of an internal PCR fragment obtained with potexvirus group-specific primers indicated that the phlox virus was distinct from PapMV, and sequence of the coat protein (CP) gene and 3' untranslated region (UTR) revealed a close relationship to Alternanthera mosaic virus (AltMV), previously reported only from Australia.. The host range was also similar to that of AltMV from Australia (AltMV-Au), and the phlox isolate reacted strongly with antiserum to AltMV-Au. The full sequence of the phlox isolate was subsequently obtained, and shown to be more closely related to PapMV in each portion of the genome than to any other extant potexvirus sequence other than AltMV-Au, for which only the CP and 3'UTR sequences are available. The phlox isolate was therefore named AltMV-PA, and the 6607 nt full sequence is presented. Additional AltMV isolates from creeping phlox and from trailing portulaca (Portulaca grandiflora) have also been isolated, suggesting that AltMV may be widespread, and may have been mis-diagnosed in the past as PapMV. The host range identified here shows that AltMV has the potential to spread to other ornamental crops.