Genetic studies of Pepino mosaic virus in Spain
Pepino mosaic virus (Potexvirus, PepMV - EPPO Alert List) was described in 1974 infecting pepino (Solanum muricatum) in Peru. During experiments on its host range in Peru, tomato was found to be an asymptomatic host. In the 2000s, tomato infections caused by PepMV were reported in Europe and North America. In Spain, PepMV was first identified in south-east Spain, and its initial location in Murcia suggested a single introduction. Since then, PepMV has caused severe epidemics in tomato crops in south-east Spain and in all tomato-growing areas along the Mediterranean coast. PepMV was also detected in the Canary Islands in 2000, causing similar symptoms. The genetic variability and population structure of PepMV was analyzed in Spain. Results showed that despite a high symptom diversity, the Spanish population was mainly composed of a single genetic type (more than 80% of the population corresponded to the European tomato strain). The Spanish population also contains, at a low frequency, isolates which were similar to those from Peru (Peruvian strain, asymptomatic on tomato) or to an isolate from the USA (US2 strain). The Peruvian and US2 strains were detected in Murcia only in 2004, but the Peruvian strain has been detected in the Canary Islands since 2000. These results suggested that PepMV has been introduced into Spain more than once. It was also observed that isolates belonging to the Peruvian an US2 strains were always found in mixed infections with the European tomato strain, and that recombinants could be identified. The authors concluded that the introduction of new strains and the appearance of new genetic types by recombination between strains represent a potential risk which should be taken into account when designing control strategies.
Sources
Pagán I, Córdoba-Sellés MC, Martínez-Priego L, Fraile A, Malpica JM, Jordá C, García-Arenal F (2006) Genetic structure of the population of Pepino mosaic virus infecting tomato crops in Spain. Phytopathology 96(3), 274-279.