By Steve Watson, Agronomy eUpdate Editor

Wheat streak mosaic has caused massive losses to the 2017 wheat crop, especially in western parts of Kansas. The complicating factor with wheat streak mosaic is that, as a virus, it does not respond to fungicides. Therefore, where it takes hold in a wheat field it can dig deeply into yields.

Kansas State University researchers have now identified a new gene that will provide resistance to the wheat streak mosaic virus. The so-called “wsm3” gene is just the third gene known to provide resistance to wheat streak and the first that can do so at temperatures of 75 degrees F and higher.

The first two genes to provide resistance to the virus were “wsm1,” which was identified by K-State scientists about 25 years ago, and “wsm2,” which was discovered by researchers at Colorado State University. But those two genes only provide protection at lower temperatures. The technology has improved considerably since then to where scientists eventually identified wsm3, also derived from wheatgrass.

“Six years ago we had a whole arm translocation. Once we had this we used directed chromosome engineering to shorten the intermediate segment to make it smaller and finally came up with a chromosome with only a small piece of wheatgrass chromosome attached. Then integrated it into wheat. The gene involved was named wsm3,” says K-State plant pathologist Bernd Friebe.

Used in combination with wsm1 or wsm2, this warmer-weather-friendly wsm3 gene could become part of a breeding mix that could give wheat producers much-needed relief from wheat streak mosaic troubles.

“We have produced this chromosome now in much, much smaller segments and we are screening these wheat lines now to see if they have maintained the wsm3 gene. This material will then be distributed to breeding companies, which will go into cultivar development,” Friebe says.

It’s been a quarter of a century of diligent research work to get to this point.