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Date: Aug 2007

[1] Tomato torrado virus - Spain (Canary Islands): 1st report
[2] Torrado disease, tomato - Spain: involvement of _Pepino mosaic virus_

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[1] Tomato torrado virus - Spain (Canary Islands): 1st report
Date: August 2007
Source: The American Phytopathological Society, Plant Disease 2007;
91(8): 1060 [edited]
<http://www.apsnet.org/pd/searchnotes/2007/PDIS-91-8-1060B.asp>

[Reference:
A. Alfaro-Fernandez et al: First Report of Tomato torrado virus in Tomato in the Canary Islands, Spain. Plant Dis. 3007; 91(8): 1060; DOI: 10.1094/PDIS-91-8-1060B]

First report of Tomato torrado virus in tomato in the Canary Islands, Spain

In 2003, greenhouse-grown tomato crops (_Lycopersicon esculentum_ Mill.) in the Canary Islands (Spain) were observed showing an initial yellowing in defined areas at the base of the leaflet that later developed into necrotic spots or an extensive necrotic area progressing from the base to tip. Fruits were also affected, showing necrotic areas and often developing cracking. Generally, the plants that were affected seemed to be burnt, their growth was reduced, and the production level was seriously damaged. Similar symptoms have been observed in Murcia (Spain) since 2001, which have been recently associated with Tomato torrado virus (ToTV) infection (2).

Between 2003 and 2006, 22 tomato samples showing 'torrado disease' symptoms were collected from different greenhouses in Las Palmas (Canary Islands, Spain). To verify the identity of the disease, double-antibody sandwich (DAS)-ELISA [Enzyme Linked Immunosorbent Assay] was performed on leaf and fruit extracts of symptomatic plants using polyclonal antibodies specific to _Potato virus Y_ (PVY), _Tomato mosaic virus_ (ToMV), _Tomato spotted wilt virus_ (TSWV), and _Pepino mosaic virus_ (PepMV). Total RNA was extracted from the 22 tomato samples and tested using one-step RT-PCR [reverse-transcription Polymerase Chain Reaction] with primers specific to PepMV (1) and ToTV (2). All analyses included healthy tomato plants as negative controls.

Of the 22 tomato samples, 5 were positive for PepMV and negative for the other viruses tested by serological analysis. However, all 22 samples were positive in RT-PCR performed with the primers specific to ToTV. Healthy plants & a water control were negative. The ToTV RT-PCR product was purified and sequenced. Analysis of one sequence showed 99 percent identity to ToTV RNA2. To our knowledge, this is the 1st report of ToTV in the Canary Islands.

References:
1. I. Pagan et al. Phytopathology 96:274, 2006.
2. M. Verbeek et al. Online Publication.
DOI:10.1007/s00705-006-0917-6. Arch. Virol., 2007.

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[2] Torrado disease, tomato - Spain: involvement of _Pepino mosaic virus_
Date: July 2007
Source: European Plant Protection Organisation (EPPO) Reporting Service no. 7, 2007/128 [edited]
<http://archives.eppo.org/EPPOReporting/2007/Rse-0707.pdf>

Studies on a new disease of tomato in Spain called 'torrado' or 'cribado'

Since spring 2001, a new disease called 'cribado' or 'torrado', has been observed on tomatoes grown under protected conditions in the region of Murcia, in Spain. Affected plants show necrotic lesions at the base of the leaflets, which later turn into shot holes (hence the Spanish name 'cribado'). Longitudinal necrotic lesions also appear on the stems, necrotic line patterns or blotches followed by deformations appear on the fruits rendering them unmarketable. Affected plants present a general burnt-like appearance (hence the Spanish name 'torrado')

In Spain, several methods were used to try to identify the causal agent (symptomatology, serology, molecular tests, electron microscopy, and transmission trials) on a large number of symptomatic tomato samples during the last 6 years. On the basis of symptomatology, it was considered that the disease mainly occurs in Murcia and Canary Islands (Tenerife, Gran Canaria) and to a lesser extent in Almeria (Andalusia), Alicante (Valencian Community), and Balearic Islands (Mallorca). Similar symptoms were observed in the provinces of Vizcaya (Basque Community), Tarragona (Catalonia), and Valencia (Valencian Community) but were finally attributed to
_Parietaria mottle virus_ (_Ilarvirus_). Preliminary results of ELISA [Enzyme Linked Immunosorbent Assay] and PCR [Polymerase Chain Reaction] analysis showed that from a total of 369 samples, 67 percent tested positive for _Pepino mosaic virus_ (PepMV; _Potexvirus_ -- EPPO Alert List). However, in transmission assays, symptoms could only be reproduced in 2 plants grafted with infected plants (the rest of the inoculated plants showed typical symptoms of PepMV). Further molecular studies showed that 89 percent of the PepMV isolates detected in diseased tomato plants corresponded to the 'Chilean 2' isolate of PepMV.

In other studies done in the Netherlands (Verbeek et al, 2007), a new virus was isolated from tomato plants in Murcia showing similar symptoms and tentatively called Tomato torrado virus (ToTV). Phylogenetic analyses suggested that this new virus might belong to a new genus (close to _Sequivirus_, _Sadwavirus_, & _Cheravirus_).
Following this report, further experiments were done in Spain and 94 samples, which had been collected in tomato glasshouses in Murcia from 2003 to 2006, were tested for the presence of this newly described virus (RT-PCR, molecular hybridization). A total of 87 samples tested positive for ToTV. In 83 of these samples, ToTV was detected in association with PepMV (mainly 'Chilean 2' isolate).

It is concluded that this new tomato disease is probably a syndrome involving ToTV and particular strains of PepMV, as well as other factors, which remain to be determined.

References:
1. Alfaro-Fernandez A, Cordoba Selles MC, Cebrian Mico MC, Font I, Juarez M, Medina V, Lacasa A, Sanchez Navarro, Pallas V, Jorda Gutierrez C (2007): Advances in the study of tomato 'Torrao' or 'Cribado'' syndrome. Boletin de Sanidad Vegetal, Plagas 33(1), 99-109.
2. Alfaro-Fernandez A, Cordoba Selles MC, Cebrian Mico MC, Font I, Juarez M, Medina V, Lacasa A, Sanchez Navarro, Pallas V, Jorda Gutierrez C (2006) Tomato necrosis disease: 'torrao' or 'cribado'.
Boletin de Sanidad Vegetal, Plagas 32 (4), 545-562.
3. Jorda C, Martinez L, Cordoba MC, Martinez O, Juarez M, Font I, Lacasa A, Guerrero MM, Cano A, Monserrat A, Barcelo N, Alcazar A (2003): El 'cribado' o 'torrao', una nueva enfermedad del cultivo del tomate? Phytoma Espana no. 152, 130-6.
4. Verbeek M, Dullemans AM, van den Heuvel JFJM, Maris PC, van der Vlugt RAA (2007): Identification and characterization of tomato torrado virus, a new plant picorna-like virus from tomato. Archives of Virology 152(5), 881-890.

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[ToTV symptoms of leaf necrosis affect the photosynthetic potential of the host and therefore may result in considerable yield loss. Recent reports suggest that the new virus is spreading. White flies are suspected to be possible vectors for ToTV. Virus particles are isometric with a diameter of approximately 28 nanometers. The viral
genome consists of 2 positive strand single-stranded RNA molecules of 7793 (RNA1) and 5389 (RNA2) nucleotides. The RNAs are encapsidated by 3 proteins with estimated sizes of 35, 26, and 23 kDa. Phylogenetic 
analyses of nucleotide and derived amino acid sequences showed that the virus is related to, but distinct from, viruses belonging to the genera _Sequivirus_, _Sadwavirus_, & _Cheravirus_ in the proposed order of the Picornavirales. It most likely represents a member of a new plant virus genus.

_Pepino mosaic virus_ (PepMV; _Potexvirus_ was originally described in Peru on pepino and has since been reported from North America (2000) and Europe (1999). Hosts include cucurbits and solanaceous species such as pepino (_Solanum muricatum_), tomatoes (mainly glasshouse grown), potato and wild _Lycopersicon_ species. Symptoms are yellow mosaic or spots on the leaves, inter-veinal chlorosis, leaf distortion, stunting, and sometimes fruit discoloration. Significant crop losses have been observed if the virus remains unchecked. It is spread by plant material, mechanical means, and grafting. Seed transmission would be unlikely in a _Potexvirus_, but further studies are needed.

_Parietaria mottle virus_ (PMoV; genus _Ilarvirus_) has been reported from Italy and Spain. Hosts include parietaria weed (wall pellitory; _Urticaceae_), tomato, French bean, English spinach, basil, and mungbean. Symptoms vary seasonally and include mosaic, mottling, or necrotic patching on leaves. The virus is transmitted by mechanical means and grafting.

Maps
Spain, including Canary Islands:
<http://www.map-of-spain.co.uk/large-map-of-spain.htm>
Provinces of Spain:
<http://www.data-spain.com/map.html>
PepMV worldwide distribution (September 2006):
<http://www.eppo.org/QUARANTINE/Alert_List/viruses/maps/PEPMV0_map.htm>
Note: data shown on this map has been generated by PQR version 4.5, therefore information published ***after December 2005*** has not yet been included.

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>
PepMV symptoms on tomato:
<http://www.defra.gov.uk/planth/pestnote/pepibig1.htm>  and
<http://www.defra.gov.uk/planth/pestnote/pepibig2.htm>
_Parietaria officinalis_:
<http://www.flogaus-faust.de/e/parioffi.htm>

Links
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>
Information on PepMV:
<http://www.eppo.org/QUARANTINE/Alert_List/viruses/PEPMV0.htm>
PepMV taxonomy:
<http://phene.cpmc.columbia.edu/ICTVdB/56001014.htm>
PMoV taxonomy:
<http://phene.cpmc.columbia.edu/ICTVdB/10002013.htm>  and
<http://md.brim.ac.cn/vide/descr551.htm>
Descriptions of all ICTV-recognised viruses via:
<http://www.ncbi.nlm.nih.gov/ICTVdb/Ictv/index.htm>
EPPO alert list:
<http://www.eppo.org/QUARANTINE/Alert_List/alert_list.htm>.  - Mod.DHA]

[see also in the archive:
Torrado disease, tomato: new virus identified 20070324.1030]

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