EPPO Alert List – Tomato fruit blotch virus (Blunervirus solani)
Why
Tomato fruit blotch virus (ToFBV - Blunervirus solani) is an emerging virus of tomato. ToFBV was first described from symptomatic tomato samples collected in Lazio (Italy) in 2018 on tomato plants showing fruit dimpling and irregular ripening. However, stored samples collected in 2012 were found to be infected by ToFBV, showing that ToFBV has been present in Italy at least since this date. A distinct isolate of the same virus was also detected in samples from Australia. The complete genome of ToFBV has been sequenced, but until now, Koch’s postulates have not been completed. Following this initial description, ToFBV has been detected in other European countries and other continents, suggesting that it might be already more widespread than originally thought and that it would be necessary to better understand its distribution, biology and epidemiology, as well as its impacts on tomato fruit production. The EPPO Panel on Diagnostics in Virology and Phytoplasmology suggested that ToFBV should be added to the EPPO Alert List.
Where
ToFBV is an emerging virus and its geographical distribution remains uncertain. In particular, records in Canary Islands and Tunisia would need to be confirmed. The NPPO of the Netherlands has intercepted in trade symptomatic tomato fruits originating from the Canary Islands (Spain), but for the moment, the presence of ToFBV has not been confirmed in tomato crops on these islands. Sequences of ToFBV isolates from Tunisia have been deposited in NCBI but were collected from potato (Solanum tuberosum), and there is no indication from other sources that ToFBV can infect potato plants.
EPPO region: Greece (mainland and Kriti), Italy (including Sicilia), Portugal, Slovenia, Spain, Switzerland.
South America: Brazil (Distrito Federal).
Oceania: Australia (no further details).
On which plants
Symptoms associated with ToFBV have been observed on field and glasshouse tomatoes (Solanum lycopersicum). If confirmed, the detection of ToFBV in potato samples (see above) would enlarge the host range of ToFBV to another economically important crop.
Damage
ToFBV affects tomato fruits, and no leaf symptoms have been reported to date. Affected fruit show irregular and blotchy ripening, dimpling and dark spots. Using transmission electron microscopy (TEM), enveloped and bacilliform virus particles (approximately 25 nm wide × 100 nm long) could be observed in samples prepared from blotched areas of the pericarp of ToFBV-infected tomato fruits. When studying fruit tissues, the highest virus concentration was found in the pericarp. In tomato seeds, ToFBV could be detected on their external tegument, but not in emerging seedlings, thus suggesting that it is not seed transmitted. In some cases ToFBV has been detected with other tomato viruses (e.g. tomato brown rugose fruit virus, pepino mosaic virus, Southern tomato virus). For the moment, the economic impact of ToFBV on tomato production remains unknown.
Transmission
Mechanical transmission tests on ToFBV in tomatoes have failed to produce infected plants and no seed transmission could be obtained. Although no vectors are known, it is suspected that the tomato russet mite (Aculops lycopersici) is involved in the 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.
Pathways
Plants for planting of tomatoes from countries where ToFBV occurs, fruit? viruliferous mite vector(s)?
Possible risks
Tomato is an economically important crop which is grown indoors and/or outdoors across the EPPO region. The emergence of a new virus directly affecting the fruit could potentially represent a serious threat to tomato fruit production. As many aspects of the biology, epidemiology, geographical distribution, host range, and economic impact of ToFBV are unknown, it is difficult to assess the risk it might present to the EPPO region. Nevertheless, it is useful that NPPOs should be made aware of the emergence of this new virus of tomato.
Sources
Beris D, Galeou A, Kektsidou O, Varveri C (2023) First report of Tomato fruit blotch fruit virus infecting tomato in Greece. New Disease Reports 48, e12219.
https://doi.org/10.1002/ndr2.12219
Blouin AG, Dubuis N, Brodard J, Apothéloz-Perret-Gentil L, Altenbach D, Schumpp O (2023) Symptomatic, widespread, and inconspicuous: new detection of tomato fruit blotch virus. Phytopathologia Mediterranea 62(3), 349-354.
Ciuffo M, Kinoti WM, Tiberini A, Forgia M, Tomassoli L, Constable FE, Turina M (2020) A new blunervirus infects tomato crops in Italy and Australia. Archives of Virology 165, 2379-2384.
Kitajima EW, Nakasu YET, Inoue-Nagata AK, Salaroli RB, Ramos-Gonzales PL (2023) Tomato fruit blotch virus cytopathology strengthens evolutionary links between plant blunerviruses and insect negeviruses. Scientia Agricola 80, e20220045.
Maachi A, Torre C, Sempere RN, Hernando Y, Aranda MA, Donaire L (2021) Use of high-throughput sequencing and two RNA input methods to identify viruses infecting tomato crops. Microorganisms 9(5), 1043.
Nakasu EY, Nagata T, Inoue-Nagata AK (2022) First report of tomato fruit blotch virus infecting tomatoes in Brazil. Plant Disease 106(8), 227.
Panno S, Ragona A, Bertacca S, Agrò G, Yahyaoui E, Dimauro B, Caruso AG, Davino S (2023) Outbreak of tomato fruit blotch virus in the most relevant tomato greenhouse production area of Sicily. Journal of Plant Pathology (early view) https://doi.org/10.1007/s42161-024-01623-1
Rivarez MP, Pecman A, Bačnik K, Maksimović O, Vučurović A, Seljak G, Mehle N, Gutiérrez-Aguirre I, Ravnikar M, Kutnjak D (2023) In-depth study of tomato and weed viromes reveals undiscovered plant virus diversity in an agroecosystem. Microbiome 11, 60.
Tiberini A, Hafsa AB, Kazuko A, Gentili A, Taglienti A, Haegeman A, Manglli A, Maachi A, Torre C, Kutnjak D, Kitajima EW et al. (2022) Tomato fruit blotch virus: an update on epidemiology, cytopathology and molecular features. Abstract of a poster presented at the Conference on Advances in Plant Virology (Ljubljana, SI, 2022-10-05/07).
EPPO RS 2020/184, 2022/143, 2022/152, 2023/221, 2023/243, 2024/016, 2024/062