The terrestrial orchid Phaius tankervilliae (Orchidaceae) infected by the mosaic Cymbidium (CymMV) postexvirus in Costa Rica

In 1996, plants of Phaius tankerilliae cultivated in a nursery in the weste rn region of the Central Valley of Costa Rica, exhibited mild to severe fol iar symptoms of chlorotic streak. Flowers from symptomatic plants were simi lar in size, shape and color to flowers from asymptomatic plants, but the f ormer showed earlier senescence. In some cases, chlorosis and white rings a ppeared in the sepals. Virus in symptomatic leaf extracts were concentrated by ultracentrifugation and separation in sucrose gradients. Negative stain ing of partially purified preparations from diseased orchid plants revealed the presence of filamentous potexvirus-like particles of 500 nm in lenght and 17 nm width. Virus particles contained a single major protein of about 28 kDa as estimated by denaturalizing poli-acrylamide gel electrophoresis ( SDS-PAGE) and a single RNA molecule of about 7kb. Infected plants showed a strong specific reaction in double antibody sandwich enzyme-linked immunoso rbent assay (DAS-ELISA) using antiserum to cymbidium mosaic virus.