MONOCLONAL ANTIBODIES FOR THE DETECTION OF TAGETES WITCHES’ BROOM AGENT
N. Loi, P. Ermacora, T.A. Chen, L. Carraro, R. Osler
Tagetes Witches’Broom disease (TWB) was first recorded in Italy in 1958, and in 1972 a phytoplasma was associated with the disease. Infected Tagetes patulus plants were used as source of inoculum for phytoplasma transmission to Catharanthus roseus. The phytoplasma was also back-transmitted from C. roseus to T. patulus and T. erectus by dodder. Three monoclonal antibodies (Mabs) were obtained against the TWB agent (TWBa); all belonging to subclass IgG1. Using ELISA and DIBA (dot immunobinding assay) it was possible to detect TWBa in experimentally inoculated periwinkle and Tagetes, and in naturally infected Tagetes. The specificity of the Mabs was also evaluated by ELISA checking 30 phytoplasmas isolated on perwinkle from different herbaceous and woody plants. Serological correlation was observed only between TWBa and a phytoplasma isolated from a yellows-infected grapevine.