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MOROCCO: TOMATO BROWN RUGOSE FRUIT VIRUS – FIRST REPORT

Monday, 20 November 2023 12:05:05

Grahame Jackson posted a new submission ‘TOMATO BROWN RUGOSE FRUIT VIRUS – MOROCCO: FIRST REPORT’

Submission

TOMATO BROWN RUGOSE FRUIT VIRUS – MOROCCO: FIRST REPORT

ProMED
https://promedmail.org/

Source: European Plant Protection Organisation (EPPO) Reporting Service 10/2023/235 [summ. Mod.DHA, edited]
https://gd.eppo.int/reporting/article-7717
The NPPO [National Plant Protection Organisation] of Morocco recently informed EPPO of the occurrence of _Tomato brown rugose fruit virus_ (_Tobamovirus_, ToBRFV – EPPO A2 List) on its territory. During the production season 2022-2023, about 10 outbreaks have been confirmed on tomato (_Solanum lycopersicum_) grown in glasshouses for fruit production. The sources of the outbreaks are infected imported seed.

ToBRFV has been a priority quarantine pest in Morocco since 2018, and official measures are taken in case of findings. They include the destruction of infected plants, restriction on cultivation of host plants and hygiene measures. In 2023, yield losses were observed, as well as increased management costs.

Communicated by:
ProMED
[_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 Europe and the Mediterranean region, where it continues to spread (see links below), as well as from China and North America, but so far not from South America. The virus was shown to affect also 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, crinkling (rugosis) on leaves; necrotic spots on petioles and calyces; 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_) has been found in tomato (ProMED posts 20191029.6751082, 20200507.7307615), as well as with TSWV in capsicum (see link below). It is thought that the respective symptoms may have been 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.
Pictures
ToBRFV on tomato:
https://gd.eppo.int/media/data/taxon/T/TOBRFV/pics/1024×0/4137.jpg and
https://gd.eppo.int/media/data/taxon/T/TOBRFV/pics/1024×0/4138.jpg
ToBRFV symptoms on capsicum:
https://agriculture.vic.gov.au/__data/assets/image/0009/555759/TOBRFV_figure-5.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 (Jordan),
https://doi.org/10.1371/journal.pone.0170429 (Israel),
https://doi.org/10.1007/s42161-023-01436-8 (TSWV co-infection, capsicum) and via
https://www.semanticscholar.org/topic/Tomato-brown-rugose-fruit-virus/3579397
ToBRFV spread:
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/,
https://www.hortidaily.com/article/9265808/we-can-eradicate-tobrfv-from-the-tomato-industry-with-our-newly-found-resistance/ and
https://www.hortidaily.com/article/9272889/commercial-tomato-variety-with-tobrfv-resistance-to-be-offered-in-early-2021/
ToBRFV seed treatment:
https://doi.org/10.1007/s10658-020-02151-1
Recent ToBRFV updates. Europe:
https://www.hortidaily.com/article/9574147/greece-tobrfv-found-in-laconia,
https://www.hortidaily.com/article/9571654/italy-tobrfv-virus-officially-confirmed- in-sardinia,
https://www.freshplaza.com/europe/article/9544392/new-measures-to-prevent-the-spread-of-the-tobrfv-virus-in-the-eu-will-apply-from-september/,
https://gd.eppo.int/reporting/article-7531 (1st report Slovakia, ex Austria) and
https://www.hortidaily.com/article/9507097/thirteen-new-tobrfv-infections-in-the-netherlands/ (first at seed production and breeding site)
International spread of tobamoviruses by seeds (review):
https://doi.org/10.5772/intechopen.70244
Virus taxonomy via:
https://ictv.global/taxonomy
EPPO A2 quarantine list:
https://www.eppo.int/ACTIVITIES/plant_quarantine/A2_list
– Mod.DHA

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