Nature, Incidence, and Symptomatology of Viruses Infecting Vanilla tahitensis in French Polynesia

A survey was carried out to identify the viruses infecting vanilla in French Polynesia and to assess their incidence. Virus identification was based on enzyme-linked immunosorbent assay (ELISA) and, for potyviruses, on the sequence of part of the coat protein and inoculation assays. Between 1998 and 1999, 3,610 vanilla plants from 49 plots in the Society Islands were indexed. Cymbidium mosaic virus (CymMV) was detected in 500 vines from 10 plots in the Leeward Islands. The data suggest that this virus has spread widely since its first detection in French Polynesia in 1986, most likely through the dissemination of symptomless infected cuttings. Viruses belonging to the Potyvirus genus were found in 674 plants from 27 plots in the four islands surveyed. Three distinct potyviruses have been identified: (i) Vanilla mosaic virus, (ii) Watermelon mosaic virus, and (iii) and a virus related to Bean common mosaic virus. The symptoms induced on Vanilla tahitensis by the three potyviruses can be differentiated from each other and from those due to CymMV. A significant proportion of the plants surveyed (97/476) were symptomatic but tested negative by ELISA for CymMV and the Potyvirus group. Odontoglossum ringspot virus was not detected in any sample tested.