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November 13, 2007
Source: The American Phytopathological Society, Plant Disease
2007; 91(10), 1364 [edited] <http://www.apsnet.org/pd/searchnotes/2007/PDIS-91-10-1364A.asp>
[Reference: H. Pospieszny et al: The first report of Tomato
torrado virus in Poland. Plant Dis; 91(10): 1364; DOI:
10.1094/PDIS-91-10-1364A]
The first report of Tomato torrado virus in Poland
In 2003 and 2004, unusual disease symptoms, including severe
stunting, malformation, and necrosis of the leaves on tomato cv.
Grace, were observed in the Wielkopolska [Greater Poland] Region
of Poland. The disease appeared to be associated with the
presence of the greenhouse whitefly _Trialeurodes vaporariorum_.
An electron microscopic examination showed the presence of
spherical virus particles approximately 25 to 28 nanometers in
diameter. The virus (designated Wal'03) was shown to be vectored
efficiently (100 percent) by _T. vaporariorum_ and poorly (50 to
70 percent) by mechanical transmission to tomato. Mechanical
inoculation or whitefly transmission caused systemic infection
on a number of hosts, including tomato, capsicum, and potato.
Viral RNA analysis revealed RNA1 (approximately 7800 basepairs)
and RNA2 (approximately 5400 bp).
The biological properties and the genomic RNA composition showed
significant similarities to that of tomato necrotic dwarf virus
(ToNDV) described from California (1) and the newly identified
tomato torrado virus (ToTV) in Spain (2). Wal'03 virus particles
reacted with ToNDV antiserum. Fragments from Wal'03 were
sequenced and
comparisons with ToTV showed 99 and 98 percent nucleotide
identity for RNA1 and RNA2, respectively. The similarity of the
symptoms on tomato plants, the morphology of virus particles,
genome composition and nucleotide sequence identities suggest
that Wal'03 and ToTV are the same.
References:
1. RC Larsen et al. Phytopathology 74: 795, 1984
2. M Verbeek _et al._ Arch. Virol. 152: 881, 2007
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[ToTV is a new virus, which appears to be spreading. Symptoms of
leaf necrosis affect the photosynthetic potential of the host
and therefore may result in considerable yield loss. ToTV was
suspected to be transmitted by whiteflies, and the results
reported above have now identified _T. vaporariorum_ as an
efficient vector.
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_, and _Cheravirus_ in the proposed
order of the Picornavirales. ToTV most likely represents a
member of a new plant virus genus.
ToNDV (?) is a poorly characterised virus reported in 1984 as a
new type of virus transmitted by whiteflies (_Bemisia tabaci_).
It is not listed by the International Committee on Taxonomy of
Viruses (ICTV). The cross-reaction of ToNDV antibodies with ToTV
particles as reported above may point towards some degree of
relatedness between these 2 viruses.
Whiteflies are both insect pests capable of reducing plant
productivity and longevity, and virus vectors. The only whitefly
genus other than _Bemisia_ identified as a virus vector is
_Trialeurodes_. In contrast to the large numbers of viruses
(genera _Begomovirus_, _Carlavirus_, _Ipomovirus_, _Crinivirus_)
transmitted by _Bemisia_, only a handful of viruses have been
found to be transmitted by _Trialeurodes_, all within the genus
_Crinivirus_.
ToTV appears to be the 1st virus from a different genus reported
for this vector.
Maps of Poland:
<http://healthmap.org/promed?v=52.1,19.4,5>
and
<http://graphicmaps.com/webimage/countrys/europe/lgcolor/plcolor.htm>
[Wielkopolskie province in west-central Poland can be located on
the map at
<http://www.lib.utexas.edu/maps/europe/poland_pol00.jpg>.
- CopyEd.MJ]
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>
_T. vaporariorum_:
<http://www.apsnet.org/online/feature/whitefly/view.asp?ID=404>
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>
Information on torrado disease research:
<http://archives.eppo.org/EPPOReporting/2007/Rse-0707.pdf>
Proposed order of Picornavirales:
<http://www.picornavirales.org>
_Crinivirus_ taxonomy:
<http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.017.0.02.htm>
Information on and viruses transmitted by _T. vaporariorum_:
<http://www.apsnet.org/online/feature/whitefly/>
ICTV virus index:
<http://www.ncbi.nlm.nih.gov/ICTVdb/Ictv/index.htm>.
- Mod.DHA]
[see also in the
archive:
Torrado disease, tomato - Spain: new findings 20070906.2944
Torrado disease, tomato: new virus identified 20070324.1030] |
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