November 24, 2005
From: American Phytopathological Society, Plant Disease Notes, November 2005 [edited] <http://www.apsnet.org/pd/searchnotes/2005/PD-89-1244C.asp>


Natural occurrence of viruses in Lycopersicon spp. in Ecuador
S. Soler, C. Lopez, and F. Nuez, Centro de Conservacion y Mejora de la Agrodiversidad Valenciana (COMAV), Camino de Vera 14, 46022 Valencia, Spain. Plant Dis. 89:1244, 2005; published on-line as DOI: 10.1094/PD-89-1244C. Accepted for publication 26 Jul 2005.

The Andean region is home of important genetic diversity for the genus _Lycopersicon_. A survey of 3 asymptomatic populations of _L. hirsutum_, 17 of _L. parviflorum_, 188 of _L. pimpinellifolium_, and 4 cultivated populations of _L. esculentum_ was made in 9 departments of Ecuador.

Samples were analyzed serologically for Tomato spotted wilt virus (TSWV), Tomato mosaic virus (ToMV), Tobacco mosaic virus (TMV), Cucumber mosaic virus (CMV), Potato virus Y (PVY), Potato virus X (PVX), Groundnut ringspot virus (GRSV), Tomato chlorosis spot virus (TCSV), and Pepino mosaic virus (PepMV). Samples positive as determined using double-antibody sandwich enzyme-linked immunosorbent assay (absorbance values 3 times higher than negative controls) were analyzed using reverse transcription-polymerase chain reaction (RT-PCR) with virus-specific primers.

_L. pimpinellifolium_ was the only species of the 4 found to be infected with viruses. In the department of Manabi, ToMV was detected in 15 of 16 plants from one population, but only a single plant was infected with PepMV. In this department, PepMV was also detected in a single-plant population that corresponded to a volunteer plant found in the wild and TSWV was detected in another plant. In Esmeraldas and Guayas, 2 single-plant populations were found infected with PepMV and CMV, respectively. TMV, PVY, PVX, GRSV, and TCSV were not detected in this survey.

Specific primers were selected for ToMV (To1/To2, genome coordinates 3498-3518/4902-4922, AJ417701), PepMV (Pe1/Pe2 genome coordinates 5030-5050/5913-5935, AJ606359), CMV (Cm1/Cm2 genome coordinates
541-561/1756-1779, D00356), and TSWV (Ts1/Ts2 genome coordinates 4078-4101/4738-4769, AF208498). Amplicons of the expected size were obtained using RT-PCR and then cloned and sequenced.

DNA fragments of ToMV, PepMV, and TSWV showed identities greater than 99 percent with respective sequences in the GenBank database. The highest identity of the CMV DNA fragment was 92 percent with an isolate from Indonesia (AB042292).

The occurrence of viruses such as CMV, ToMV, and TSWV in coastal Ecuador was not surprising. However, infected plants were not found among the samples collected in the departments of Azuay, Carchi, El Oro, Imbabura, Loja, and Pichincha in eastern Ecuador. _L. chilense_, _L. chmielewskii_, _L. parviflorum_, and _L. peruvianum_ were
previously reported as natural hosts of PepMV in central and southern Peru (2), and the virus was also detected in _L. esculentum_ in Chile (1).

Our results show that PepMV now occurs in wild _L. pimpinellifolium_ populations along the Pacific coast of the South American continent and that it must have efficient means of transmission, although no specific vectors have as yet been identified for this virus.

To our knowledge, this is the 1st report of PepMV in Ecuador and _L. pimpinellifolium_ as a natural host of PepMV.

References:
(1) M. Munoz et al. Fitopatologi 37:67, 2002.
(2) S. Soler et al. J. Phytopathol. 150:49, 2002.

--
ProMED-mail
<promed@promedmail.org>

[The significance of this report is that PepMV has been detected for the 1st time in Ecuador in wild populations of _Lycopersicon pimpinellifolium_ along the Pacific coast of the South American continent. Potexviruses are extremely infectious but they are not known to be naturally spread by vectors. PepMV is easily spread via
contact with infected plants. PepMV has been detected in the potato cultivar 'Yungay' growing in the Andes in Peru. Moreover, 14 percent of tested accessions in the potato germplasm at the International Potato Center in Peru are infected with PepMV. More research is required to determine the risks of PepMV infection in potato. Spread from tomato to potato may be possible under field conditions in southern Europe.

PepMV induced serious losses in tomato fruit quality in trials at Efford in the UK in 2003. In the 'worst case' scenario, these losses could be in the order of GBP 37.5 million [USD 64.4 million] in the GBP 79 million [USD 135 million] UK industry, assuming that the disease becomes endemic in all tomato fruit production areas. In
practice, losses may not be as great. Because the UK industry is based almost exclusively on production of high-quality fruit, with virtually no tomato processing industry, any losses of quality would be significant. Any drop in quality could be catastrophic for producers.

Contrary to experimental results in the UK, numerous field and several experimental observations in the Netherlands and a few other EU countries indicate that PepMV has only a very minor or a non-significant economic impact on tomato production on average. More damage might be expected if PepMV-affected plants are also attacked by _Verticillium_ sp.

The economic impact due to PepMV is also influenced by the marketing system in a country. In the UK, only Class 1 fruit is profitable. This is not the case in several other EU Member States where, as a consequence, the grower can still profitably sell fruit of less than top quality.

Link:
The following link contains a comprehensive review of the pest risk analysis for PepMV:
<http://www.ingentaconnect.com/content/bsc/jph/2002/00000150/00000002/art00712>
- Mod.DH]

[see also in the archive:
Pepino mosaic, surveys, EPPO - United Kingdom 20050120.0201
Pepino mosaic virus, tomato - Hungary (1st report) 20050205.0395
Pepino mosaic virus, tomato - Hungary (02):1st report, correction 20050206.0401
Pepino mosaic virus, tomato - Hungary (02):1st report, correction 20050206.0402
2004
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Pepino mosaic virus, tomato - Slovakia: 1st report 20040703.1778
2003
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Pepino mosaic virus - EPPO countries 20031222.3112
2001
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Pepino mosaic virus, tomato - Finland 20010916.2240
Pepino mosaic potexvirus, tomato - Spain 20011231.3140
Pepino mosaic potexvirus, natural hosts - Spain 20011231.3141
2000
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Pepino mosaic potexvirus: added to EPPO alert list 20000208.0180
Pepino mosaic potexvirus - France (Guipavas) 20000505.0687
Pepino mosaic potexvirus, tomatoes - Spain 20001013.1750]