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Tomato brown rugose fruit and pepino mosaic viruses - Russia: ex Morocco, interception

A ProMED-mail post
http://www.promedmail.org
ProMED-mail is a program of the
International Society for Infectious Diseases
http://www.isid.org

Date: Mon 23 Dec 2024
Source: Bayane Al-Yaoum [in Arabic, machine trans., summ. Mod.DHA, edited]
https://tinyurl.com/4bn7wj6k

Russian agricultural authorities recently prevented entry of a shipment of Moroccan tomatoes in the Kaliningrad region. Laboratory tests found 10 cases weighing 1110 kg [2447 lb] to be infected with tomato brown rugose fruit virus and pepino mosaic virus. Both are among the prohibited organisms subject to ban according to Russian standards. The shipment of Moroccan tomatoes was accompanied by re-export certificates from Belgium, France, and the Netherlands.

[Byline: Said Ait Oumzid]

--
Communicated by:
ProMED

[ToBRFV
---------
_Tomato brown rugose fruit virus_ (ToBRFV) was identified as a new member of the genus _Tobamovirus_ (type member _Tobacco mosaic virus_, TMV) in Jordan and soon after in Israel (see links below). Since then, it has also been reported from various other regions worldwide and continues to spread. The virus was shown to also affect capsicum and has been detected in both plants and seeds of both crops. ToBRFV symptoms on tomato vary depending on host cultivar but may include chlorosis, mottling, mosaic, and crinkling (rugosis) on leaves; necrotic spots on petioles and calyces; and yellowish mottling, brown spots, and rugosis on fruit to make them unmarketable. On capsicum, leaf symptoms are similar; fruits may be deformed with yellow mottling or green stripes. Almost 100% incidence was reported for some outbreaks in tomato, but not every fruit on an infected plant may show symptoms.

ToBRFV (like many tobamoviruses) is seed transmitted and can also be spread by mechanical means, contaminated equipment, as well as with plant or other materials. It is very stable and can remain infectious for months outside a host. Bumblebees, which are used widely as commercial pollinators in glasshouse tomato production, have been shown to be effective vectors of ToBRFV (see link below). Volunteer crop plants and solanaceous weed species are likely pathogen reservoirs. The Tm-22 resistance gene used in some tomato cultivars to protect from other tobamoviruses (such as _Tomato mosaic virus_) does not appear to be effective against ToBRFV. Disease management relies mainly on exclusion but may include phytosanitation (disinfecting tools, removing crop debris) and control of virus reservoirs. Use of certified clean seeds or crop transplants is crucial. Research on possible seed treatments to eliminate the virus is being carried out (see link below). Tomato seeds are traded widely and are known to pose a risk of spreading viruses and other pathogens internationally (e.g., ProMED post 20140122.2222560).

Coinfection of ToBRFV with _Pepino mosaic virus_ (genus _Potexvirus_) and _Tomato spotted wilt virus_ (TSWV; genus _Orthotospovirus_) have been found in tomato (ProMED posts 20191029.6751082, 20200507.7307615), as well as with TSWV in capsicum (see link below). Other coinfecting partners may be expected to exist, with _Peru tomato mosaic virus_ suspected (_Potyvirus_; ProMED post 20240124.8714440). It is thought that respective symptoms in coinfections may be due to either virus or synergism. Further research is needed to clarify a potential role of ToBRFV in coinfections and to determine whether its presence in coinfections may have led to earlier cases of misdiagnosis and delayed identification of this new virus.

PepMV
--------
_Pepino mosaic virus_ (PepMV, genus _Potexvirus_) was first identified on pepino (_Solanum muricatum_) in South America. It is spreading in the Americas and Europe and has also been reported from a few locations in Asia and Africa. PepMV can also infect potato and aubergine, but serious symptoms appear to occur only in tomato. Symptoms may include blotches and scarifications on fruit; and mottling, distortion, and necrosis on leaves and young shoots. The virus can cause significant economic losses, especially in glasshouse tomatoes, due mainly to reduction of fruit quality.

PepMV spreads very rapidly and is highly contagious. Specific insect vectors have not been identified. The virus is transmitted by mechanical means (including contaminated tools, human or insect activities, and plant-to-plant contact) and grafting, and with infected plant material (including insufficiently cleaned seed batches containing contaminated plant debris). True seed transmission (that is, via the embryo rather than the seed coat) is uncommon in potexviruses and appears unlikely for PepMV, but more research is needed. Disease management is usually focused on phytosanitation and use of certified clean seed and tomato explants.

Different strains of the virus exist for pepino and tomato. Coinfections have earlier been reported with _Potato virus S_ (genus _Carlavirus_) and _Tomato torrado virus_ (genus _Torradovirus_). As mentioned above, coinfection with the new _Tomato brown rugose fruit virus_ (genus _Tobamovirus_) was reported (ProMED post 20191029.6751082), and it was thought that the observed symptoms on tomatoes may have been due to either virus or to synergism. As for ToBRFV, further studies are needed to clarify the effects of these interactions of PepMV with other viruses on crop damage.

Due to diligent and strict testing of imports (see ProMED posts 20210721.8533380, 20201109.7930136), Russia had long been successful in keeping national tomato production free of PepMV. However, recently PepMV was detected in the outlying enclave Kaliningrad during a large-scale crop survey (ProMED post 20230714.8711143), followed by detection within the main Russian territory (ProMED post 20240711.8717503). The origin of these infections was not known at the time of detection, but the report above may indicate a possible route of entry into Russia.

Maps
Locations of Russian regions and republics:
https://www.russianlessons.net/russia/images/russian-regions.gif

Pictures
ToBRFV on tomato:
https://gd.eppo.int/media/data/taxon/T/TOBRFV/pics/1024x0/4137.jpg and
https://gd.eppo.int/media/data/taxon/T/TOBRFV/pics/1024x0/4138.jpg
ToBRFV symptoms on capsicum:
https://agriculture.vic.gov.au/__data/assets/image/0009/555759/TOBRFV_figure-5.jpg
PepMV symptoms on tomato:
https://www.agdia-emea.com/wp-content/uploads/2014/03/Tomato-Pepino-Mosaic-Virus-e1445510159191.jpg and
https://media.sciencephoto.com/image/c0015940/800wm/C0015940-Pepino_mosaic_virus_infected_leaf.jpg
Healthy pepino plants:
https://i.pinimg.com/originals/47/24/ae/4724ae19353d0525be547b75ba2d99f6.jpg

Links
Information and characterisation of ToBRFV:
https://gd.eppo.int/taxon/TOBRFV (with distribution and host list),
https://doi.org/10.1007/s00705-015-2677-7 and
https://doi.org/10.1007/s42161-023-01436-8 (TSWV co-infection, capsicum)
ToBRFV spread:
https://doi.org/10.1094/PDIS-11-23-2413-PDN (new reservoir hosts),
https://doi.org/10.1371/journal.pone.0282441 (new reservoir hosts) and
https://doi.org/10.1371/journal.pone.0210871 (by pollinators)
Tomato resistance breeding:
https://www.hortidaily.com/article/9544570/intermediate-resistance-ir-to-tobrfv-in-tomato-varieties-confirmed/
ToBRFV seed treatment:
https://doi.org/10.1007/s10658-020-02151-1
International spread of tobamoviruses by seeds (review):
https://doi.org/10.5772/intechopen.70244
Information on PepMV:
https://gd.eppo.int/taxon/PEPMV0 (with pictures),
https://doi.org/10.1079/cabicompendium.43661,
https://doi.org/10.1111/j.1364-3703.2009.00600.x,
https://www.ontario.ca/page/management-pepino-mosaic-virus-greenhouse-tomatoes,
https://www.freshplaza.com/article/175250/New-advice-to-help-tomato-growers-eradicate-Pepino-Mosaic-Virus/ and
https://doi.org/10.1007/s10658-015-0664-1
Virus taxonomy via:
https://ictv.global/taxonomy
- Mod.DHA]