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[1] _Wheat streak mosaic virus_
[2] _Soil-borne wheat mosaic virus_
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[1] _Wheat streak mosaic virus_
Date: April 2009
Source: Plant Disease [edited]
<http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-93-4-0430B>
In August of 2005, seeds of wheat (_Triticum
aestivum_) breeding line 6065.3 tested positive for _Wheat
streak mosaic virus_ (WSMV; genus
_Tritimovirus_) by a WSMV-specific reverse transcription
(RT)-PCR assay. The sequence of the 200-bp amplicon was 99
percent identical with WSMV isolates from Turkey and the United
States, and 96 to 97 percent identical to isolates from
Australia.
As a result, an extensive survey of 3 cereal experimental trials
and 105 commercial wheat crops grown on the South Island of New
Zealand was conducted during the 20052006 summer to determine
the distribution of WSMV. Wherever possible, only symptomatic
plants were collected.
Symptoms on wheat leaf samples ranged from very mild mosaic to
symptomless. In total, 591 leaf samples suspected to be
symptomatic were tested for WSMV by a double-antibody sandwich
(DAS)- ELISA [enzyme-linked immunosorbent assay]. Of the 591
symptomatic samples, 81 tested positive.
ELISA results were confirmed by RT-PCR [reverse
transcription-polymerase chain reaction]. The expected size
fragment was amplified from each of the 81 ELISA-positive
samples. The positive samples represent 30 of 56 wheat cultivars
(54 percent) collected from 28 of 108 sites (26 percent) sampled
in the growing regions from mid-Canterbury to North Otago.
These results suggest that WSMV is widespread in New Zealand
both geographically and within cultivars. WSMV is transmitted by
the wheat curl mite (_Aceria tosichella_), which had not been
detected in New Zealand despite repeated and targeted surveys.
WSMV is of great economic importance in some countries, where
the disease has been reported to cause total yield loss.
Although WSMV is transmitted by seeds at low rates (0.1 to 0.2
percent), it is the most likely explanation of the spread of the
disease in New Zealand.
Reference:
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BSM Lebas et al: 1st report of _Wheat streak mosaic virus_ on
wheat in New Zealand. Plant Disease 2009; 93(4), 430; DOI:
10.1094/ PDIS-93-4-0430B
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******
[2] _Soil-borne wheat mosaic virus_
Date: January 2009
Source: Australasian Plant Pathology [edited] <http://www.publish.csiro.au/nid/39/paper/AP08082.htm>
_Soil-borne wheat mosaic virus_ (SBWMV) was identified using
transmission electron microscopy, enzyme-linked immunosorbent
assay (ELISA) and reverse transcription-polymerase chain
reaction (RT-PCR) tests in 2 out of 5 samples collected from a
wheat (_Triticum aestivum_) plant showing severe leaf mosaic.
The plant was also infected with _Barley stripe mosaic virus_
and _Barley yellow dwarf virus_-MAV and -PAV [strains of BYDV].
A further 28 out of 200 wheat samples tested positive for SBWMV
using ELISA. A comparison of 11 New Zealand SBWMV isolates
indicated that they were all identical and had 98 percent
nucleotide sequence identity with SBWMV isolates from the United
States, subgroup New York-Illinois. At the location of the SBWMV
outbreak the vector, _Polymyxa graminis_, was detected by PCR
and the identity was confirmed by sequencing. This is the 1st
report of SBWMV in New Zealand.
Reference:
----------
BSM Lebas et al: Investigation of an outbreak of Soil-borne
wheat mosaic virus in New Zealand.
Australasian Plant Pathology 2009, 38(1): 85-90; DOI:
10.1071/AP08082
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ProMED-mail
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[_Wheat streak mosaic virus_ (WSMV; genus _Tritimovirus_) is
prevalent in North America, Russia, Eastern Europe, and has also
been reported from Australia and Argentina. It can infect wheat,
maize (some cultivars), grasses, and also oats and barley in
experimental inoculations. Heavy WSMV infection can cause
complete crop failure in wheat. The virus is spread by the wheat
curl mite, but can also be mechanically transmitted and seed
transmitted at a very low level. Control of the mite vector is
difficult but disease management may include controlling
volunteer wheat and grassy weeds to minimise inoculum. However,
it is particularly noteworthy that WSMV appears to have been
spread throughout New Zealand in the absence of its mite vector
and entirely by contaminated seed. This illustrates once more
the importance of seed certification, even for pathogens where
seed transmission occurs only at low levels.
_Soil-borne wheat mosaic virus_ (SBWMV; genus _Furovirus_)
occurs in many countries from various parts of the world. It
causes one of the few diseases of winter wheat that can destroy
an entire crop of a susceptible cultivar. Symptoms vary and may
include mild green to prominent yellow leaf mottling, rosetting,
and moderate to severe stunting of plants. SBWMV is transmitted
by the soil-inhabiting fungus _Polymyxa graminis_, an obligate
parasite in the roots of many grasses. It survives in soil and
crop residues protected by the fungus, and can be spread in
contaminated soil, by water, and mechanical means. It is not
seed-transmitted.
Disease management relies mainly on use of resistant wheat
cultivars.
Since for both viruses the New Zealand isolates are reported to
be most closely related to isolates from the USA, this must be
suspected to be the origin of their introduction.
Maps of New Zealand:
<http://www.backpack-newzealand.com/images/new-zealand-map.gif>
and
<http://healthmap.org/promed?v=-42.4,172.7,5>
Pictures
WSMV leaf symptoms:
<http://www2.dpi.qld.gov.au/images/8658.jpg>
Wheat curl mite
<http://www.nwroc.umn.edu/Cropping_Issues/2006/Issue8/wht_curl_mite.jpg>
SBWMV leaf symptoms:
<http://www.apsnet.org/education/LessonsPlantPath/soilborneWheat/images/fig05.jpg>
Wheat field with patch affected by SBWMV:
<http://www.ipm.uiuc.edu/diseases/series100/rpd102/102-2.gif>
Links
WSMV disease information:
<http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0017/44027/Wheat_streak_mosaic_and_the_wheat_curl_mite_-_Primefact_99.pdf>
and
<http://plantpathology.tamu.edu/Texlab/Grains/Wheat/wsmv.html>
WSMV taxonomy and description:
<http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.057.0.06.001.htm>
SBWMV disease information:
<http://www.ipm.uiuc.edu/diseases/series100/rpd102/index.html#symptoms>
and <http://www.ipm.uiuc.edu/diseases/series100/rpd102/index.html#cycles>
WMV taxonomy and description:
<http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.027.0.01.001.htm>
_P. graminis_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=266382>
Review of wheat viruses:
<http://muextension.missouri.edu/explore/agguides/crops/g04318.htm>
- Mod.DHA]
[see also
in the
archive:
2008
----
Cereal viruses - USA: (OR, KS) 20080416.1363
2007
----
Wheat streak mosaic virus - Australia (TAS) 20070928.3211 Stripe
rust, wheat & wheat streak mosaic - Australia (SA, WA)
20070830.2860 Wheat diseases - USA (KS): crop loss 20070518.1574
2006
----
Wheat streak mosaic virus - Australia (WA) (02) 20060914.2601
Wheat streak virus - USA 20060608.1606 Wheat streak mosaic virus
- Australia (WA): 1st Report 20060514.1364
2005
----
Wheat streak mosaic - Australia (NSW) 20051029.3159
2004
----
Wheat streak mosaic virus - Argentina: 1st report 20040922.2614
2003
----
Wheat streak mosaic, first report - Australia (Canberra)
20030417.0941 2000
----
Wheat & rye mosaic viruses, soilborne 20000331.0483]
