First report of onion yellow dwarf virus, leek yellow stripe
virus, and garlic common latent virus in garlic in Washington
State |
A
ProMED-mail post
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International Society for Infectious Diseases
February 17, 2005
Source: American Phytopathological Society, Plant Disease Notes
[edited]
First report of onion yellow dwarf virus, leek yellow stripe
virus, and garlic common latent virus in garlic in Washington
State
H. R. Pappu, Department of Plant Pathology, Washington State
University, Pullman 99164; B. C. Hellier and F. M. Dugan,
USDA-ARS, Western Regional Plant Introduction Station,
Washington State University, Pullman 99164. Plant Dis. 89:205,
2005; published on-line as DOI: 10.1094/PD-89-0205C. Accepted
for publication 23 Nov 2004.
Washington State ranks 4th in the country in garlic (_Allium
sativum_) production (2). The impact of viruses on garlic
production may be significant in Washington State, but little is
known about the occurrence or identity of specific viruses (2).
The USDA-ARS Western Regional Plant Introduction Station (WRPIS)
collects, maintains, and
distributes garlic accessions. As part of the regeneration
process, accessions are grown in field conditions at the WRPIS
farm in Pullman, WA.
In June 2004, several WRPIS accessions developed symptoms
indicative of viral infection, primarily chlorotic spots and
yellow stripes on leaves and scapes. Cultivars Georgia Fire and
Georgia Crystal showed more than 90 percent incidence of
symptomatic plants. Some chlorotic spots appeared similar to
those caused by Iris yellow spot virus on other _Allium_ spp.
such as _A. cepa_.
However, enzyme-linked immunosorbent assay (ELISA), as well as
polymerase chain reaction (PCR) with IYSV-specific primers (1)
did not reveal the presence of IYSV. Degenerate, group-specific
primers to potyviruses (3) and carlaviruses (courtesy of S. D.
Wyatt) were used on total nucleic acids extracted from each
symptomatic plant
with reverse transcription (RT)-PCR. The samples (n = 26) gave
an RT-PCR product of the expected size with the group-specific
potyvirus RT-PCR test. One sample was positive with the
carlavirus group RT-PCR test.
RT-PCR products from both tests were cloned and sequenced.
Comparisons with sequences in GenBank showed that all but one
had Onion yellow dwarf virus (OYDV), whereas one sample had a
mixed infection of OYDV and Leek yellow stripe virus. Sequence
analysis showed that the carlavirus was Garlic common latent
virus. Sequence
identities ranged from 95-99 percent for each of the viruses
when compared with those available in GenBank. All samples were
then tested for each of these viruses with commercially
available antisera. Results of ELISA confirmed the findings of
RT-PCR.
To our knowledge, this is the 1st report for each of these
garlic viruses from Washington State. This finding prompts the
need for evaluating all garlic accessions for the potential
impact of these viruses on garlic germ plasm conservation and
distribution.
References:
(1) L. J. du Toit et al. Plant Dis. 88:222, 2004.
(2) R. M. Hannan and E. J. Sorensen. Crop Profile for Garlic in
Washington. Washington State University Coop Extension and the
U.S. Department of Agriculture, 2002.
(3) S. S. Pappu et al. J. Virol. Methods 41:9, 1993.
[OYDV is transmitted by _Myzus persicae_
and other aphid species, or mechanically to onions and other
crops such as garlic, leek and some narcissus species. It is not
spread by seed, but infected bulbs (transplants and volunteers)
always produce diseased plants and serve as a source of
contamination for following seasons, especially when aphid
populations are high. Disease management relies on use of
disease-free transplants and crop rotation out of onion
production for at least 3 years. Other disease management
recommendations include isolation from other susceptible crops
or volunteer [self-sown] onions. Insecticides may suppress
vector populations but generally are not necessary or effective.
Garlic common latent carlavirus is of minor significance, but
combined with other viruses can cause severe disease in Europe,
South and Central America, India and China. Leek yellow stripe
potyvirus causes severe disease in autumn and winter leek crops
in western Europe and is probably present in leek production
areas worldwide.
Links: <http://highplainsipm.org/HpIPMSearch/Docs/YellowDwarf-Onion.htm>
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