Tomato brown rugose fruit virus
ToBRFV, Jordanvirus, Tobamoviren
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).
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.
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.
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.
The yield reduction caused by the virus is difficult to estimate, as the symptom expression varies greatly depending on the variety. However, yield losses of 20% can be assumed, even for varieties tolerant to ToBRFV. Varieties that show little tolerance to the virus may suffer complete plant death. In tomato, known resistance to tobamoviruses has been shown to be ineffective against ToBRFV. In bell bell pepper, tobamovirus resistance genes are effective against ToBRFV. Resistant bell pepper varieties show a hypersensitivity reaction as a resistance response to ToBRFV. Since 2022, the first, new tomato cultivars that are tolerant or resistant to ToBRFV, according to the breeders, have become available from many seed producers.
ToBRFV is currently classified as a quarantine pathogen and measures to prevent the introduction and spread of the virus are in place.
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.
According to the reclassification of quarantine pests (Regulation (EU) 2016/2031), ToBRFV is considered a "new pest" and is currently handled as a quarantine pest (QSO). Implementing Regulation (EU) 2023/1032 regulates measures to prevent the introduction and spread of the virus.
We are a National Reference Laboratory (NRL) for the detection of phytopathogenic quarantine pathogens, including the detection of plant pathogenic viruses. This also obliges us to use internationally specified methods of analysis and to participate in international ring tests.
Participation in the Euphresco project: Validation of diagnostic tests for the detection and identification of Tomato brown rugose fruit virus in tomato and pepper seeds.
Official plant protection service: Information on the risk of introduction and measures
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: 13.02.2024