Begomoviruses of tomato in Nicaragua
In Central America, many vegetable crops have been severely affected by whitefly-transmitted viruses since the mid-1980s. Significant yield losses have been noted, in particular in bean (Phaseolus vulgaris) and tomato (Lycopersicon esculentum) crops. In Nicaragua, diseases caused by whitefly-transmitted viruses were observed in the tomato-growing area of Tisma in the 1970s, but at low incidence. In the early 1980s, these diseases also appeared in Sebaco valley, in association with high populations of whiteflies. In 1998, they affected 100% of tomato crops in Sebaco valley and other regions of the country with drastic yield reductions. At the end of the 1990s, this became a nation-wide problem and tomato production virtually vanished from Nicaragua. After hurricane Mitch, whitefly-transmitted viruses were momentarily suppressed, probably because whitefly populations were highly reduced. But in 1999, whitefly populations increased again and 100 % of tomato fields were infected, showing various types of symptoms (yellow mottling, crinkling, curling, severe stunting).
Tomato samples were collected from August 1998 to January 1999 from 9 locations (11 fields) representing the major tomato-growing regions of Nicaragua. Results showed that symptomatic tomato samples were indeed infected by begomoviruses in all studied regions. DNA sequence analysis and comparison with other begomovirus occurring in the Americas showed that 4 different begomoviruses could be distinguished. No mixed infections were found. In 3 different regions, a virus showing 97-99 % similarity to Sinaloa tomato leaf curl begomovirus (EPPO Alert List) was found. Sinaloa tomato leaf curl begomovirus occurs in Costa Rica and Mexico and its most probable presence in Nicaragua led the authors to think that this virus is probably widespread in Central America. Two of the other viruses presented 92% and 94 % sequence similarity with Sida golden mosaic and Tomato leaf crumple begomoviruses, respectively. A fourth virus was closely related to a tomato-infecting virus from Honduras, and tentatively called Tomato mild mottle virus.
Sources
Rojas, A.; Kvarnheden, A.; Valkonen, P.T. (2000) Geminiviruses infecting tomato crops in Nicaragua.
Plant Disease, 84(8), 843-846.