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Occurrence and Partial Characterization of a New Mechanically Transmissible Virus in Mashua from the Ecuadorian Highlands

January 1998 , Volume 82 , Number  1
Pages  69 - 73

S. L. Soria , Department of Plant and Soil Sciences, College of Agricultural Sciences, Delaware Agricultural Experiment Station, University of Delaware, Newark, 19717 ; R. Vega , AMDE Corp., Ambato, Ecuador ; V. D. Damsteegt , Foreign Disease and Weed Laboratory, USDA-ARS Fort Detrick, Frederick, MD ; L. L. McDaniel , American Type Culture Collection, Rockville, MD ; and S. L. Kitto and T. A. Evans , Department of Plant and Soil Sciences, University of Delaware

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Accepted for publication 17 September 1997.

Mashua (Tropaeolum tuberosum) is a tuber crop indigenous to the Andean highlands and of economic value to its native people as a food and medicinal crop. Field plants often exhibit symptoms typical of virus infection, including interveinal chlorosis, leaf cupping, distortion, and stunting. Using an herbaceous host range, at least 1 mechanically transmissible virus was detected in each of 10 accessions. All virus isolates tested reacted to potyvirus group antiserum in indirect enzyme-linked immunosorbent assays (ELISA). Results of monoclonal antibody testing using antigen coated plate (ACP) ELISA, where virions are disrupted to expose cryptotopes, indicated that isolate Tt 4 has epitopes in common with maize dwarf mosaic potyvirus A (MDMV-A). Polyclonal antiserum produced to purified preparations of the Tt 4 isolate reacted in indirect ELISA to Tt 4, the common strain of potato potyvirus Y (PVY-C), less strongly to tobacco etch potyvirus (TEV) and potato potyvirus A (PVA), but not to 11 other potyviruses, including MDMV-A. Conversely, the Tt 4 isolate reacted strongly in indirect ELISA to antisera to bean common mosaic potyvirus (BCMV) and watermelon mosaic potyvirus 2 (WMV-2), but not antisera to 12 other potyviruses. Our data suggest that isolate Tt 4 is a distinct potyvirus closely related to and sharing external epitopes with PVY-C, TEV, PVA, WMV-2, and BCMV, and buried epitopes with MDMV-A. The virus has been tentatively named Tropaeolum mosaic potyvirus (TropMV). A survey of T. tuberosum in Ecuador revealed that TropMV was widespread, being detected by ACP-ELISA in 34 of 46 accessions at the National Institute for Agricultural Research's Santa Catalina Research Station, Quito, and all eight production fields surveyed.

© 1998 The American Phytopathological Society