Silencing Wheat and Barley Scab

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 Steven 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 Crop Production and Pest Control Research Unit at West Lafayette, Ind.

Under the initiative, farmers and scientists work together to combat scab—also known as Fusarium head blight—one 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 plant’s scab resistance also disappears temporarily.

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 Agriculture’s chief scientific research agency.