Wheat head infected
with scab. Click the image for more information about it.
Silencing Wheat and Barley Scab
By Don Comis
May 26, 2006
A new test to find scab-resistance genes in wheat and barley seed
heads uses the plants natural viral defense mechanism to temporarily
silence the gene to be tested. The test is an adaptation of a
technique called Virus-Induced Gene Silencing (VIGS).
Agricultural Research Service (ARS) geneticist
Scofield and colleagues developed the test with funds from the
U.S. Wheat and Barley Scab Initiative
managed by ARS. Scofield is in the ARS
Production and Pest Control Research Unit at West Lafayette, Ind.
Under the initiative, farmers and scientists work together to combat
scabalso known as Fusarium head blightone of the most
devastating wheat and barley diseases worldwide. Currently, there are only a
few wheat and barley varieties with effective levels of resistance to scab.
The test temporarily incapacitates wheat or barley genes thought to be
important to scab resistance, to see if the plants scab resistance also
Scofield began experimenting with VIGS when he first came to ARS in
2002. With it, he found four genes key to leaf rust resistance in wheat and
barley plants. He is working to adapt VIGS to find resistance genes for each
major wheat and barley disease, one at a time.
Before this VIGS-based test, there was no way to assess probable genes
for scab resistance other than through breeding, or by inserting them into
tissue cells and then regenerating whole plants for testing. The new test is
much quicker and more efficient since it can be done shortly after a plant is
infected with a virus, without waiting to grow a new plant.
VIGS has been used for about 10 years. Scientists first used it with
tobacco, then tomatoes, potatoes and Arabidopsis thaliana.
ARS is the U.S. Department of
Agricultures chief scientific research agency.