Abstract
Pepino mosaic virus (PepMV) was first described from pepino (Solanum muricatum) with distinct yellow mosaic symptoms in the coastal region of Peru. It was shown to be in the Potexvirus genus and capable of infecting tomato (Lycopersicon esculentum) and potato (Solanum tuberosum). Systemic infections in tomato were symptomless. The virus is transmitted readily by mechanical means and at very low levels in tomato seed. The latter is however considered an important mechanism for international spread. The first reports of PepMV in Europe came from tomato in the Netherlands and the UK in 1999. Since then, the virus has been reported from many other European countries, as well as some on other continents including USA, Canada, Morocco, Chile and China. Following its initial discovery in Europe, nucleic acid sequencing showed the European isolates were found to be similar, to each other and to isolates from North America suggesting a common source. What is now considered the tomato type strain is also clearly distinct from the original PepMV isolate from Pepino (Solanum muricatum). This original strain is now referred to as the Peruvian strain of PepMV. More recently two tomato isolates (US1 and US2) have been found in the USA that differ considerably from the European tomato type strain (Maroon-Lango et al., 2005). Very recently both the Peruvian strain as well as the US2 strain were detected in Spain. Further isolates that appear similar to US2 have subsequently been found in a number of other European countries. Overall the potential dangers of these new strains to tomato and other Solaneceous crops in Europe is not yet understood. There is also currently no clear picture of the true impact that PepMV has on the European tomato industry. For this reason, the EU have agreed to fund research project (PEPEIRA is an EU-funded project aimed at developing an EU-wide Pest Risk Assessment (PRA) for PepMV. The project will investigate the epidemiology and economic impact of the virus in order to allow a robust and scientifically-justified assessment of the risk posed by this pathogen to the European tomato industry. This includes a true assessment of the economic impact on tomato crops growing in Member States with different climatic and market conditions and the role of seed transmission in the spread of PepMV. The project will also address the increased risk posed by new, biologically and genetically distinct strains of PepMV that have appeared in Europe and elsewhere in the last two years and have the potential to be far more damaging. The project will also address the issue of developing validated diagnostic protocols, to be published via EPPO that can be used with confidence by National Plant Protection Organisations (NPPOs) within the EU and laboratories in other countries that trade with the EU. In addition to a strong and focussed science program, the project also mobilises an impressive consortium, including all EU laboratories with a proven track record of PepMV research, with extensive plant virus and plant health expertise from all Member States where PepMV poses a potential risk. Adoption of the new PRA will allow EU Plant Health services to develop a consensus on appropriate measures to prevent PepMV becoming significantly detrimental to the EU tomato industry. In addition to the work milestoned in the EU-funded PEPEIRA project, further Defra Plant Health Division work will be carried out on improved seed treatment methods.
United Kingdom