Source: European Plant Protection Organisation (EPPO) Reporting Service 01/2024/016 [summ. Mod.DHA, edited]
Tomato fruit blotch virus_ (ToFBV) is being added to the EPPO Alert List. It is an emerging virus in the region which was first described in 2020 from Italy in tomato samples collected in 2018 showing fruit dimpling and irregular ripening. However, stored samples collected in 2012 were also found to be infected by ToFBV, showing that ToFBV had been present in Italy at least since then.
The complete genome of ToFBV has been sequenced, but until now, Koch's postulates have not been completed. ToFBV has since been detected in other European countries and other continents, suggesting that it might be more widespread. Sequences of ToFBV have been reported from potato in Tunisia, but further confirmation of potato as a host ofToFBV is needed.
Electron microscopy has detected enveloped, bacilliform virus particles (ca. 25-100 nm) in blotched areas of ToFBV-infected tomato fruits. ToFBV could also be detected in tomato seeds, but not in emerging seedlings, suggesting that it is not seed transmitted. In some cases ToFBV was detected with other tomato viruses (e.g. _Tomato brown rugose fruit virus_, _Pepino mosaic virus_, _Southern tomato virus_).
Mechanical transmission of ToFBV in tomatoes has failed to infect plants, no seed transmission could be obtained. No vectors are known so far, but it is suspected that the tomato russet mite (_Aculops lycopersici_) may be involved in disease transmission, as it has often been observed on ToFBV-infected tomato plants. Over long distances, trade of infected plants seems to be the most likely pathway.
The emergence of a new virus directly affecting tomato fruit production could potentially represent a serious threat to stake holders. However, risk assessment is difficult at present, with many aspects of biology, epidemiology, geographical distribution, host range and economic impact of ToFBV as yet unknown.
[After _Tomato fruit blotch virus_ (ToFBV, genus _Blunervirus_; new binomial name _Blunervirus solani_) was first identified in tomatoes with uneven blotchy fruit ripening and dimpling grown in open field cultivation in Italy, the complete genome of the virus was sequenced and characterised as quadripartite, positive-sense, single-stranded RNA.
Highest sequence identities were found with _Tea plant necrotic ring blotch virus_ and _Blueberry necrotic ring blotch virus_ of genus _Blunervirus_ (family Kitaviridae). ToFBV was ratified by the International Committee on Taxonomy of Viruses (ICTV) in 2021 as a third member of this new genus.
ToFBV has currently been recorded in around 10 countries worldwide, with more than 10 genomic sequence variants available. Co-infections with other tomato viruses were found in some symptomatic tissues (see links below). In co-infections (e.g., see _Tomato brown rugose fruit virus_, ProMED post 20240124.8714440), respective symptoms may be due to either virus or synergism. As stated above, clear proof of any symptoms being due specifically to ToFBV (Koch's postulates) is required.
Additional news stories:
https://www.fruitjournal.com/tofbv-su-pomodoro-prima-volta-in-sicilia/ (in Italian)
Information on ToFBV
Previous reports and characterisation of ToFBV:
Description & information for genus _Blunervirus_:
Virus taxonomy via:
EPPO alert list: