Australia
April 23, 2007Key
points:
• New seed testing technology to detect presence of wheat streak
mosaic virus
• Rapid progress being made towards a practical test for growers
An innovative research project supported by growers and the
Australian Government through the
Grains Research and Development
Corporation (GRDC) has completed the important first stage
in developing a test to detect the presence of wheat streak
mosaic virus (WSMV) in wheat seeds.
The discovery of WSMV in Australia resulted in a major setback
for wheat breeding programs and since then it has been a GRDC
priority to develop tools and techniques for detecting and
managing the virus and its carrier, the wheat curl mite.
Dr Roger Jones, principal plant virologist at the
Department of Agriculture
and Food Western Australia (DAFWA), said the ability to test
for the presence of WSMV in seeds would be a key weapon in
growers’ disease management strategies.
“Wheat streak mosaic virus was widely distributed across the
Western Australian wheat belt in 2006, and could pose a
significant threat in 2007 if conditions favour the build-up of
the disease,” Dr Jones said. “The virus is transmitted at low
levels through the embryo of wheat seeds and planting infected
seed stocks introduces foci of infection into the crop.
“Growers need to know if WSMV is present before sowing, because
if infected seed stocks are sown and the infected seeds
germinate, the wheat curl mite can transfer the virus from
WSMV-infected seedlings to healthy plants and eventually cause
high levels of infection across the entire crop”.
Dr Jones said the GRDC research project has already developed an
interim test for presence of WSMV in seed coats, and work has
now begun on developing a seed embryo test.
“We have made a substantial leap towards WSMV detection in grain
seeds,“ he said.
“We have developed a polymerase chain reaction (PCR) test that
detects the presence of WSMV in the coat of the seed, but this
is an interim test because it only identifies if the crop from
which the seed came was exposed to the virus. It does not
identify the actual level of seed transmission through embryo
infection to seedlings.
“We are currently working to develop systems for PCR testing on
the embryo of the seed, which will provide this information.”
Having been responsible for developing the seed coat test, Dr
Geoffrey Dwyer, senior research officer for molecular
diagnostics at DAFWA, has been given the task of streamlining
embryo-testing procedures.
“Embryo testing shows true virus transmission, because if
infected seed embryos germinate they give rise to an infected
plant,” Dr Dwyer said. “A test to detect WSMV in the embryo of
the seed will give a true reflection of what the initial virus
levels will be in the resulting crop, which has practical
benefits for growers.”
Dr Dwyer said development of the seed test began in May last
year, and the rapid progress of the research had been very
pleasing.
“In a short space of time we’ve developed the seed coat test,”
he said. “Our research is now pushing towards embryo testing,
and we hope to develop a quantitative test this year so growers
will be given the percent of WSMV infected seeds in the sample.” |
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