Tomato mottle mosaic virus (ToMMV) is a tobamovirus found in a Solanum lycopersicum sample collected in Mexico in 2009. To assess the possible presence of ToMMV in Europe, accessions from a historic seed collection were tested by real-time RT-PCR and Illumina sequencing. ToMMV was identified in historical seed accessions produced in France, the Netherlands and Spain. Three different near complete genome sequences were obtained, each corresponding to the country in which the seeds had been produced. Positive samples from France and Spain could be related to the same production location and year, respectively, while the identical genome sequences from the Netherlands were obtained from samples produced in different locations and years between 1981 and 2007. The latter could be due to the fact that the Dutch seed accessions had been repacked in the past at the same location and time as accessions with a relatively high virus load from 2007. This indicates that possibly only the seeds from 2007 originated from ToMMV-infected plants, while the detection of ToMMV in the older seed accessions resulted from cross contamination. This data shows that ToMMV has been around in Europe before its first description and is possibly more widespread than currently known.

With the emergence of high throughput sequencing (HTS) technologies, the discovery of new plant viruses has outpaced their biological characterization. However, it is crucial to understand the biology of these viruses to evaluate the risks they pose for the production of crops and natural ecosystems and to manage them properly. In 2018, Physostegia chlorotic mottle virus (PhCMoV) was detected in Austria in a Physostegia plant (Lamiaceae) using HTS, and subsequent prepublication data sharing associated the presence of the virus with severe fruit symptoms on important crops like tomato, eggplant, and cucumber across nine European countries. This discovery led to a collaborative effort to understand better the virus's genetic diversity, host range, symptomatology, and distribution. Still, specific knowledge gaps remained. In this study, the authors address these gaps by examining the transmission mode, prevalence, and disease severity of PhCMoV. Bioassay and field survey confirmed the causal association between the presence of the virus and symptoms on tomato and eggplant. The investigation also mapped out the historical and geographic footprint of the virus, spanning back 30 years and including a new location, Switzerland. Based on field survey, PhCMoV was found to naturally infect 11 new host plant species across seven families, extending the host range of PhCMoV to 20 plant species across 14 plant families. Greenhouse assays with mechanical inoculation showed that yield losses could reach 100% depending on the phenological stage of the plant at the time of infection. The study also identified a polyphagous leafhopper species (Anaceratagallia sp.) as the natural vector of PhCMoV. PhCMoV was widespread in diversified vegetable farms in Belgium where tomato is grown in soil, occurring in approximately one-third of such farms. However, outbreaks were sporadic and it can be suggested that they were associated with specific cultural practices, such as the cultivation of perennial plants in tomato tunnels that can serve as a host for both the virus and its vector. To further explore this phenomenon and better manage the virus, studying the ecology of the Anaceratagalliae vector would be beneficial.