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Date: 15 Nov 2007
Source: Checkbiotech [edited]
<http://www.checkbiotech.org/green_News_Genetics.aspx?infoId=16158>

Scientists of Plant Research International of Wageningen UR [University and Research Centre] have identified the virus that causes great damage in tomato cultivation in Mexico. The disease is known as Marchitez, which means withered. The name of the new virus is Tomato marchitez virus [ToMarV]. The virus causes leaf necrosis and serious damage to the fruits, resulting in a strong yield reduction. Whitefly is one of the vectors of the virus.
Identification of the virus now makes it possible to develop resistant cultivars.

Tomato marchitez virus is found to be closely related to Tomato torrado virus [ToTV], earlier discovered in Spain, which causes the damaging Torrado disease in tomato. The viruses were both fully characterised and described as new species. Both viruses are now classified into the new [proposed] plant virus genus Torradovirus.

It is remarkable that in a short period of time, 2 new viruses have been found and described that can, on the basis of their unique characteristics, be ascribed to a new plant virus genus.

[Source: M. Verbeek et al. (2007). Tomato marchitez virus, a new plant picorna-like virus from tomato related to Tomato torrado virus.
Archives of Virology, online publication <http://www.springerlink.com/content/gj515nlw824g7323/>.]

--
Communicated by:
ProMED-mail <promed@promedmail.org>

[Additional information from the source: the new virus was isolated from a tomato plant from the state of Sinaloa in Mexico. This plant showed symptoms locally known as marchitez disease, including severe leaf necrosis beginning at the base of the leaflets and necrotic rings on the fruits.

A virus was isolated from the infected plant consisting of isometric particles with a diameter of approximately 28 nanometers. The viral genome consisted of 2 (+)ssRNA molecules of 7221 (RNA1) and 4898 nucleotides (RNA2). The viral capsid contained 3 coat proteins of 35,
26 and 24 kDa, respectively. The characteristics of symptoms, morphology, coat proteins, and RNAs were similar to those of the previously described Tomato torrado virus (ToTV). Sequence analysis of the entire viral genome showed that this new virus is related to, but distinct from, ToTV. For this new virus, the name Tomato marchitez virus (ToMarV) is proposed.

ToTV causes leaf necrosis resulting in considerable yield loss. The virus appears to be spreading, and whiteflies (_T. vaporariorum_) were shown to be vectors. Phylogenetic analyses showed that ToTV is related to, but distinct from, viruses belonging to the genera _Sequivirus_, _Sadwavirus_, and _Cheravirus_ in the proposed order of the Picornavirales. ToMarV and ToTV both share unique features that clearly distinguish them from other plant picorna-like viruses. These
2 viruses are likely to belong to the same new genus for which the name Torradovirus was recently proposed by the ICTV (International Committee on Taxonomy of Viruses) study group on plant picorna-like viruses. Another new virus, Tomato apex necrosis virus (ToANV), may also be related.

Map:
Mexico:
<http://www.mexico.us/map.htm>
<http://healthmap.org/promed?v=24,-102.5,5>
Veracruz:
<http://www.travelamap.com/mexico/veracruz.htm>

Pictures
ToTV symptoms:
<http://www.deruiterseeds.com/files/Torrado_Virus_website_070221.pdf>
ToTV particles, electron micrograph:
<http://www.seedquest.com/News/releases/2007/graphics/18419a.jpg>

Links
Story also at:
<http://www.bionity.com/news/e/74329/?WT.mc_id=ca0068>
Wageningen UR Plant Research:
<http://www.plantsciencesgroup.nl/>
News release about the new ToTV:
<http://www.seedquest.com/News/releases/2007/february/18419.htm>
Characterisation of ToTV:
<http://www.springerlink.com/content/qk2617331j112m4p/fulltext.pdf>
Proposed order of Picornavirales:
<http://www.picornavirales.org>
ICTV virus index:
<http://www.ncbi.nlm.nih.gov/ICTVdb/Ictv/index.htm>
- Mod.DHA]

[see also in the archive:
Tomato torrado virus - Poland: (Greater Poland), 1st report 20071113.3684 Torrado disease, tomato - Spain: new findings 20070906.2944 Torrado disease, tomato: new virus identified 20070324.1030]
 

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