APS Homepage

Poster: Diseases of Plants: Disease Detection & Diagnosis


Tomato yellow mottle virus (ToYMoV): characterization of a newly emergent begomovirus associated with tomato disease in Costa Rica.
M. MALIANO (1), M. Rojas (1), T. Melgarejo (2), M. Macedo (3), N. Barboza (4), A. Inoue Nagata (3), R. Gilbertson (5) (1) UC Davis, U.S.A.; (2) Universidad Nacional Agraria La Molina, Peru; (3) University of Brasilia, Brazil; (4) Universidad de Costa Rica

Tomato production in Costa Rica is affected by diseases caused by whitefly-transmitted begomoviruses. Since the early 1990s, the main virus involved was the New World (NW) bipartite Tomato yellow mottle virus (ToYMoV), which was associated with stunting and yellow mottling. To fulfill Koch’s postulates, putative full-length were obtained. Nicotiana benthamiana and tomato seedlings inoculated with the ToYMoV DNA-A and DNA-B clones developed stunting and yellow mottling of leaves, confirming the infectivity of the clones. Sequence analysis revealed that ToYMoV is closely related to bipartite tomato-infecting begomoviruses from Mexico and Guatemala. Multimeric clones were generated and used to assess the host range of ToYMoV. More recently, the NW bipartite Tomato leaf curl Sinaloa virus (ToLCSiV) and the invasive Old World (OW) monopartite Tomato yellow leaf curl virus (TYLCV) were introduced to Costa Rica where they have caused yield losses. Pseudorecombinants made between infectious DNA-A and DNA-B clones of ToYMoV and ToLCSiV did not induce symptoms. Tomato plants inoculated with cloned DNAs of TYLCV, ToLCSiV and ToYMoV alone or in mixtures revealed that symptoms of ToLCSiV and ToYMoV appeared earlier than those of TYLCV. However, within 14 days after inoculation, TYLCV symptoms became dominant, although ToLCSiV and ToYMoV were still detected at high levels. These results will be discussed in terms of synergy among these viruses.