Sl. Soria et al., OCCURRENCE AND PARTIAL CHARACTERIZATION OF A NEW MECHANICALLY TRANSMISSIBLE VIRUS IN MASHUA FROM THE ECUADORIAN HIGHLANDS, Plant disease, 82(1), 1998, pp. 69-73
Mashua (Tropaeolum tuberosum) is a tuber crop indigenous to the Andean
highlands and of economic value to its native people as a food and me
dicinal crop. Field plants often exhibit symptoms typical of virus inf
ection, including interveinal chlorosis, leaf cupping, distortion, and
stunting. Using an herbaceous host range, at least 1 mechanically tra
nsmissible virus was detected in each of 10 accessions. All virus isol
ates tested reacted to potyvirus group antiserum in indirect enzyme-li
nked immunosorbent assays (ELISA). Results of monoclonal antibody test
ing using antigen coated plate (ACP) ELISA, where virions are disrupte
d to expose cryptotopes, indicated that isolate Tt 4 has epitopes in c
ommon with maize dwarf mosaic potyvirus A (MDMV-A). Polyclonal antiser
um produced to purified preparations of the Tt 4 isolate reacted in in
direct 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 t
he 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 i
solate Tt 4 is a distinct potyvirus closely related to and sharing ext
ernal epitopes with PVY-C, TEV, PVA, WMV-2, and BCMV, and buried epito
pes with MDMV-A. The virus has been tentatively named Tropaeolum mosai
c potyvirus (TropMV). A survey of T. tuberosum in Ecuador revealed tha
t TropMV was widespread, being detected by ACP-ELISA in 34 of 46 acces
sions at the National Institute for Agricultural Research's Santa Cata
lina Research Station, Quite, and all eight production fields surveyed
.