Draft Rapid Pest Risk Analysis (PRA) for: Tomato mottle mosaic virus
Tomato mottle mosaic virus (ToMMV) was first described in tomato crops from Mexico in 2013. Since then, it has been reported from tomato crops in an increasing number of countries around the world, and first reported from the EU in 2015. ToMMV is known to infect solanaceous crops (mainly tomato, peppers, and aubergine). It is closely related to tomato brown rugose fruit virus (ToBRFV) that has been shown to overcome the Tm-1 and Tm/Tm-22 resistance genes to tobamoviruses. There is also a high amino-acids sequence similarity between ToMMV and tobacco mosaic virus (TMV) and tomato mosaic virus (ToMV) with diagnosis of ToMV and TMV using serological methods having the potential to have be mis-identified and to actually be ToMMV, meaning that ToMMV could be more widespread than initially thought. Currently there have been no reports of damage or symptoms in commercial tomato fruit production. However, there are a couple of disease reports of tomatoes exhibiting ToMMV symptoms at specific production sites in Israel and Mauritius. Data is unavailable on the varieties grown in Israel and it is unknown if they were resistant varieties or not but the report from Mauritius were on varieties that had the Tm-22 resistance gene. The mechanism of this “resistance breaking” is unclear but it is thought that unusually high temperatures in the shadehouses caused the heat sensitive genes that convey resistance to fail. Despite the two isolated incidences of symptom expression, it is thought to be less damaging than ToBFRV. There is some evidence to suggest that many cultivars containing the Tm22 gene may already be resistant or partially resistant against ToMMV and it may be less of a threat than other high risk tobamoviruses such as ToBRFV.
It is the conclusion of this PRA that statutory action is not appropriate for ToMMV. The addition of the gene that conveys resistance to ToMV in current commercially available tomato varieties is also very effective against ToMMV. Officially described in 2013 ToMMV has been present in Dutch tomato seed since at least 1977, as well as being misidentified as ToMV in Brazil, Iran, and China in the past. In this time no major outbreaks have been reported, with no evidence of significant economic impacts being found (although the uncertainty around misidentifications as ToMV means it is likely unreported from some areas). The evidence of impacts from Mauritius are thought to have been the result of exceptional circumstances (the unusually hot summer caused the heat sensitive resistance gene to breakdown and allowed for symptom expression). If ToMMV was as damaging as ToBFRV (to which it is often compared) we would expect to have seen more reports of outbreaks and higher impacts than have currently been reported and seen globally.
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- United Kingdom