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: Fri 7 Feb 2020
Source: Australasian Plant Disease Notes [abridged, edited] <https://link.springer.com/article/10.1007%2Fs13314-020-0378-x>
Ref: DA Lovelock et al. (2020): _Tomato mottle mosaic virus_ intercepted by Australian biosecurity in _Capsicum annuum_ seed.
Australasian Plant Dis. Notes 15, 8; DOI: 10.1007/s13314-020-0378-x.
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_Tomato mottle mosaic virus_ (ToMMV), a _Tobamovirus_ species closely related to _Tomato mosaic virus_ (ToMV), _Tobacco mosaic virus_ (TMV), and the newly identified _Tomato brown rugose fruit virus_ (ToBRFV), was 1st reported in Mexico [and] has now been detected in China, USA, Spain, and Israel. The spread of the virus to new regions is potentially through seed, like other tobamoviruses. The virus is thought to pose a serious risk to capsicum (_Capsicum annuum_) and tomato (_Solanum lycopersicum_) crops as it may break resistance used to control other tobamoviruses, similarly to ToBRFV [see ProMED-mail post http://promedmail.org/post/20200206.6959141].
Since April 2019, all capsicum and tomato seeds imported to Australia have been tested for ToBRFV as a part of regulations imposed by the Department of Agriculture. In May 2019, an imported shipment of approximately 6000 capsicum seeds was submitted for testing on-shore.
A total of 15 sub-samples (400 seeds per sample) was tested using a one-step RT-PCR. Nine [sub-samples] produced an amplicon of 811 base pairs (bp). Sequencing indicated a 98%-99% nucleotide (nt) identity to the same region in ToMMV isolates and less than 90% nt identity to ToBRFV, ToMV, and TMV isolates. Sequences [were] confirmed by high throughput sequencing and bioinformatics analysis.
The contaminated capsicum seeds were destroyed or re-exported. This is the 1st report of ToMMV in _Capsicum annuum_ seed and follows on from the detection in tomato seed in Israel (2016), highlighting that ToMMV is likely seed-borne and is a risk of introduction through contaminated seed into regions where it has not been previously found.
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Communicated by: ProMED-mail <promed@promedmail.org>
[_Tomato mottle mosaic virus_ (ToMMV; genus _Tobamovirus_, type member _Tobacco mosaic virus_, TMV) can affect tomato and capsicum, resulting in unmarketable fruits in both crops. Symptoms may include necrotic lesions, chlorosis, distortion, and mottle on leaves, as well as necrosis on fruits. A disease incidence of up to 87% has been reported in tomato. The virus has also been reported in aubergine in mixed infection with TMGMV (_Tobacco mild green mosaic virus_), but its role in symptom development in this crop is as yet unclear. Chickpea has been reported as an asymptomatic host.
ToMMV is very stable and can be spread by mechanical means (human activities, insect damage, plant-to-plant contact) with contaminated agricultural tools, infected plant material (cuttings, tomato transplants, crop debris), contaminated soil, water, and by insect pollinators used in some commercial crops. Volunteer crop plants and solanaceous weed species are potential pathogen reservoirs. Similar to ToBRFV (see ProMED-mail post http://promedmail.org/post/20200206.6959141), resistance genes used in some tomato cultivars to protect from other tobamoviruses, such as ToMV, do not appear to be effective against ToMMV.
Many tobamoviruses are seed transmitted, and its fast international spread suggested that this is also the case for ToMMV, at least in tomato and capsicum. The Australian Department of Agriculture, Water & Environment (see link below) states that one consignment each of capsicum seeds for sowing from the Netherlands and Spain as well as 2 consignments of tomato seeds for sowing from the USA have tested positive for ToMMV. While virus transmission to seedlings germinated from infected seeds remains to be confirmed, the evidence above for its presence on or in commercial seed confirms the potential of introducing the virus to new areas in this manner.
For some tobamovirus species, seed coat surface sterilisation is effective in preventing transmission to new seedlings, suggesting that these viruses are carried on the outside of seeds. However, for some species such as _Cucumber green mottle mosaic virus_ (see previous ProMED-mail posts in the archives), surface sterilisation of seeds does not seem to prevent transmission, suggesting these viruses may be carried within the endosperm since seed-transmitted tobamoviruses are thought to be absent from embryos.
Disease management of tobamoviruses relies mainly on exclusion, but may include phytosanitation (disinfecting of tools, removal of crop
debris) and control of weed reservoirs. Use of certified clean seeds or seedling transplants is crucial. Among the seed-borne viruses, tobamoviruses are currently considered a risk for crop production worldwide due to increasing global seed trade.
Maps
Australia (with states):
<https://www.interkart.de/media/catalog/product/p/o/pod10th103_103_australia_physical.jpg>
Pictures
ToMMV symptoms on tomato:
<https://apsjournals.apsnet.org/na101/home/literatum/publisher/aps/journals/content/pdis/2017/pdis.2017.101.issue-5/pdis-10-16-1504-re/20170402/images/medium/pdis-10-16-1504-re_f4.gif>
Links
Information on ToMMV:
<https://www.agriculture.gov.au/import/goods/plant-products/seeds-for-sowing/emergency-measures-tommv-qa>
(including details of seed consignments tested in Australia), <https://www.researchgate.net/publication/312230831_Molecular_and_biological_characterization_of_Tomato_mottle_mosaic_virus_and_development_of_RT-PCR_detection>
(characterisation),
<https://gd.eppo.int/taxon/TOMMV0>,
<https://www.biorxiv.org/content/10.1101/063255v1.full> (Spain), <https://link.springer.com/article/10.1007/s10658-019-01762-7>
(Brazil) and
<https://virologyj.biomedcentral.com/articles/10.1186/s12985-016-0676-2>
(China)
International spread of tobamoviruses by seeds (review):
<https://www.researchgate.net/publication/321639141_Seed_Transmission_of_Tobamoviruses_Aspects_of_Global_Disease_Distribution>
Virus taxonomy via:
<https://talk.ictvonline.org/taxonomy/>
- Mod.DHA
HealthMap/ProMED map available at:
Australia: <http://healthmap.org/promed/p/186>]
[See Also:
Tomato brown rugose fruit virus - Spain: 1st rep (AN)
http://promedmail.org/post/20200206.6959141
2019
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Cucumber green mottle mosaic virus, melon - New Zealand ex Australia:
intercept http://promedmail.org/post/20191220.6850116
Virus double infection, tomato - Netherlands: (ZH)
http://promedmail.org/post/20191029.6751082
Tomato brown rugose fruit virus - China: 1st rep (SD)
http://promedmail.org/post/20190903.6654138
Tomato brown rugose fruit virus - UK, Turkey: 1st reps
http://promedmail.org/post/20190722.6580891
Tomato brown rugose fruit virus - Mexico: alert
http://promedmail.org/post/20190429.6448297
Tomato brown rugose fruit virus - Germany: 1st rep (NW)
http://promedmail.org/post/20190117.6264517
2018
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Cucumber green mottle mosaic virus, melon - New Zealand ex Australia:
intercept http://promedmail.org/post/20180903.6005465
2016
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Cucumber green mottle mosaic virus - Australia: (WA)
http://promedmail.org/post/20160728.4375420
Cucumber green mottle mosaic virus - Germany
http://promedmail.org/post/20160510.4211865
2015
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Tomato mosaic virus - Israel: (Negev)
http://promedmail.org/post/20151015.3717154
and additional items on tobamoviruses in the archives]
Topics
Species
