First report of Nemesia ring necrosis virus in North America in ornamental plants from California.

During the last several years, two California propagators have detected what was believed to be the tymovirus Scrophularia mottle virus (ScrMV) in several ornamental plant species on the basis of enzyme-linked immunosorbent assay (ELISA) using a ScrMV antibody system. Symptoms were generally mild, ranging from nonsymptomatic to a mild mosaic. Our laboratory confirmed the presence of a tymovirus in one Verbena sp. and two Diascia spp. cultivars on the basis of dsRNA analysis that showed bands of approximately 6,400 and 300 nucleotides representing the genomic and coat protein subgenomic RNAs, respectively. While these plants and those that were experimentally infected (Nicotiana benthamiana and N. clevelandii) also tested positive for ScrMV by ELISA, the host range did not match that published for ScrMV, notably the lack of symptoms in Chenopodium quinoa and the lack of systemic infection in Datura stramonium. A similar host range result was reported in Europe for another tymovirus that cross reacts with S...