Tomato brown rugose fruit virus
ToBRFV, Jordanvirus, Tobamoviren
Profile
ToBRFV belongs to the tobamoviruses, these are very persistent, highly infectious, plant pathogenic viruses that are transmitted mechanically and via seeds.
ToBRFV first appeared in Israel and Jordan in 2014/2015 ("Jordan virus"). In Austria, the virus was confirmed for the first time in 2021. ToBRFV is considered a quarantine pathogen (QSO).
Biology
Tobamoviruses are rod-shaped, extremely persistent, long-lived, and highly infectious plant pathogenic viruses. In addition to ToBRFV, they include tomato mosaic virus (ToMV), tobacco mosaic virus (TMV), or cucumber green mottle mosaic virus (CGMMV). Tobamoviruses can survive and remain infectious for extended periods of time on seed coats, cultivation tools, glasshouse surfaces, hands, clothing, and also on soil particles. They are very easily transmitted mechanically, but are also transmitted via seed. There are no animal vectors for tobamoviruses, but ToBRFV is mechanically transmitted by bumblebees. When young tomato plants are infected with ToBRFV, the virus is systematically distributed throughout the plant, and is detectable in all plant parts. In contrast, when older tomato plants are infected, ToBRFV is not found in all plant parts.
Damage symptoms
Affected tomato fruit may show yellow spots or lack of coloration, but also brown and wrinkled areas ("rugose fruit"). Typical are mosaic-like discolorations, but also bulging and deformation of the leaves. In some cases, necrosis of the sepals can be observed. Varieties that show little tolerance to the virus may experience complete plant death. In the outbreaks in Austria, the following symptoms could be observed: fruits not ripening, small, deformed, partly chlorotic leaves at the shoot tips and chlorotic leaf spots.
Distribution
ToBRFV first appeared in Israel in 2014, and was described as "Tomato brown rugose fruit virus," a new tobamovirus, in 2016. In Austria, the virus was first detected in 2021, with outbreaks confirmed in three provinces. ToBRFV outbreaks have now been documented in at least 35 countries worldwide.
Propagation and transmission
The primary route of spread happens via infected seeds and seedlings. Since tobamoviruses are very easily transmitted mechanically, further spread in production facilities occurs via working personnel (hair, clothing, hands, cell phones, shoes, etc.), via tools (all cultivation tools, watering tools, etc.) and via glasshouse inventory (harvesting carts and crates, all storage surfaces and glasshouse surfaces, etc.). Other routes of infection include infected plant residues from previous crops, resprouting seeds, infected soil, irrigation water or nutrient solutions, and mechanical transmission via bumblebees. ToBRFV is very persistent. For example, studies have shown that it can survive on hands and gloves for at least two hours, and on some glasshouse surfaces for up to half a year. Since the production of tomatoes in closed production areas under surveillance is allowed in many European member countries since 2021, even in case of an outbreak of ToBRFV, an infection of stocks by consumed infected fruit vegetables has to be considered.
Wirtschaftliche Bedeutung
Die Ertragsreduktion durch das Virus ist schwer einzuschätzen, da die Symptomausprägung sortenabhängig sehr unterschiedlich ist. Von Ernteverlusten von 20 % auch bei ToBRFV toleranten Sorten ist aber auszugehen. Bei Sorten die wenig Toleranz gegenüber dem Virus zeigen kann es zum völligen Absterben der Pflanzen kommen. Bei der Tomate haben sich bekannte Resistenzen gegen Tobamoviren als unwirksam gegenüber dem ToBRFV erwiesen. Bei Paprika sind Tobamovirenresistenzgene gegen das ToBRFV wirksam. Resistente Paprikasorten zeigen als Resistenzreaktion gegen das ToBRFV eine Hypersensitivitätsreaktion. Seit 2022 stehen von vielen Saatgutproduzent:innen erste, neue Tomatensortensorten zur Verfügung, die laut den Angaben der Züchter:innen tolerant bzw. resistent gegen das ToBRFV sind.
Das ToBRFV ist zurzeit als Quarantäneschaderreger eingestuft und Maßnahmen, um die Einschleppung und Verbreitung des Virus zu verhindern, sind gültig.
Prevention and control
If plants are infected with tobamoviruses, as with all plant pathogenic viruses, no curative (=healing) measures are possible. This means that the prevention of infections and their spread is of utmost importance.
The use of healthy, infection-free seed and young plant material, as well as strict adherence to and monitoring of all essential hygiene measures in the production plants, and regular checks of the stocks for symptoms, are therefore indispensable preventive measures.
Phytosanitary status
According to the reclassification of quarantine pests (Regulation (EU) 2016/2031), ToBRFV is considered a "new pest" and is currently managed as a quarantine pest organism (QSO). Implementing Regulation (EU) 2020/1191 regulates measures to prevent the introduction and spread of the virus.
Fachinformation
Wir sind Nationales Referenzlabor (NRL) für den Nachweis von phytopathogenen Quarantäneschaderregern, unter anderem auch für den Nachweis von pflanzenpathogenen Viren. Damit sind wir auch verpflichtet, international vorgegebene Analysemethoden zu verwenden und an internationalen Ringtests teilzunehmen.
Teilnahme am Euphresco-Projekt: Validation of diagnostic tests for the detection and identification of Tomato brown rugose fruit virus in tomato and pepper seeds.
Services
We detect tobamoviruses and also ToBRFV in plants and in seeds by molecular biology. As a standard procedure for ToBRFV, a real-time PCR method (RT-qPCR) is used. If needed, conventional RT-PCR and sequence analysis can be used to confirm the virus. Analysis usually takes two to three business days (approximately four business days for sequence analysis).
Last updated: 21.02.2023
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