Tomato brown rugose fruit virus (Tobamovirus- ToBRFV): addition to the EPPO Alert List
Why: Tomato brown rugose fruit virus (Tobamovirus, ToBRFV) was first identified on tomatoes in Jordan in 2015 (EPPO RS 2016/024), outbreaks have recently occurred in Germany (EPPO RS 2019/012), in Italy (EPPO RS 2019/013) and in Mexico (EPPO RS 2019/014) where the virus causes major concerns for growers of tomato and capsicum. As ToBRFV is an emerging virus and tomato is an important crop in the EPPO region, the EPPO Secretariat decided to add it to the EPPO Alert List.
Where:
EPPO region: Germany (under eradication), Israel (first disease symptoms in 2014), Italy (Sicilia), Jordan (first identified in 2015).
America: Mexico (under eradication).
Asia: Israel, Jordan.
On which plants: Tomato (Solanum lycopersicum) and capsicum (Capsicum sp.) are the main hosts. Inoculation experiments showed that Nicotiana benthamiana, N. glutinosa, N. sylvestris, N. tabacum (tobacco) develop symptoms and that weeds such as Chenopodiastrum murale and Solanum nigrum may act as reservoirs for ToBRFV. Eggplant (Solanum melongena) and potato (S. tuberosum) did not show symptoms after inoculation of the virus and ToBRFV was not found when the plants were subsequently tested by ELISA.
Damage: On tomatoes, symptoms vary depending on varieties. Tomato cultivars with the Tm-22 resistance gene (used against other tobamoviruses) are susceptible to ToBRFV. On tomato, foliar symptoms include chlorosis, mosaic and mottling with occasional leaf narrowing. Necrotic spots may appear on peduncles, calyces and petioles. Fruit show yellow or brown spots, with rugose symptoms rendering the fruits non-marketable. Fruits may be deformed and have irregular maturation. In the paper describing the first finding in Israel, diseased plants had 10 to 15% symptomatic fruit. In Jordan, in the first reported outbreak, disease incidence reached almost 100%. On capsicum, foliar symptoms include deformation, yellowing and mosaic. Capsicum fruits are deformed, with yellow or brown areas or green stripes.
Pictures are available at https://gd.eppo.int/taxon/TOBRFV/photos.
Transmission: ToBRFV is transmitted by seed, contact (contaminated tools, hands, clothing, direct plant-to-plant contact), and propagation material (grafts, cuttings). Tobamoviruses can remain infective in seeds, plant remains and contaminated soil for months. They are found in the seed coat and the endosperm, which could explain why conventional seed disinfection treatments are not fully effective to control them. Even if transmission from seed to seedling is low, further dissemination by contact (e.g. during transplantation of seedlings or regular handling of the crop) allows a rapid spread within a glasshouse.
The disease was first observed in autumn 2014 in Israel and further spread occurred across the entire country within one year, because of human-assisted spread and trade of infected seeds or seedlings.
Pathway: Seed, plants for planting from countries where ToBRFV occurs. The virus is also spread locally by contact.
Possible risks: Tomato and capsicum are important crops grown in the entire EPPO region under protected conditions. Symptoms of the disease makes the fruit unmarketable. Once the virus is introduced in an area, control measures are very limited and mainly rely on elimination of infected plants and strict hygiene measures. Testing methods (ELISA, RT-PCR) are available to detect the virus in the seed. It therefore seems desirable to avoid its further introduction and spread within the region.
EPPO RS 2016/024, 2019/012, 2019/013, 2019/014, 2019/015
Panel review date - Entry date 2019-01
Sources
Dombrovsky A, Smith E (2017) Seed transmission of tobamoviruses: aspects of global disease distribution, pp 234-260. In: Jose C. Jimenez-Lopez (ed.). Seed Biology. IntechOpen. 338 p. http://doi.org/10.5772/intechopen.70244
JKI (2018). Express – PRA zum Tomato brown rugose fruit virus https://pflanzengesundheit.julius-kuehn.de/dokumente/upload/ToBRFV_express-pra.pdf
Luria N, Smith E, Reingold V, Bekelman I, Lapidot M, Levin I, et al. (2017) A new Israeli Tobamovirus isolate infects tomato plants harboring Tm-22 resistance genes. PLoS ONE 12(1). e0170429. https://doi.org/10.1371/journal.pone.0170429
Sagarpa-Senasica (2018) Guía de síntomas de Tomato brown rugose fruit virus (ToBRFV). 19 p.
Sagarpa-Senasica (2018) Medidas de manejo elegibles para: Tomato brown rugose fruit virus. Version 1.1. 15 p.