Helping wheat defend itself against damaging viruses

Wheat diseases caused by a host of viruses that might include wheat streak mosaic, triticum mosaic, soil-borne mosaic and barley yellow dwarf could cost producers 5 to 10 percent or more in yield reductions per crop, but a major advance in developing broad disease-resistant wheat is on the horizon.

John Fellers, molecular biologist for the U.S. Department of Agriculture's Agricultural Research Service, and Harold Trick, plant geneticist for Kansas State University, have led an effort to develop a patent-pending genetic engineering technology that builds resistance to certain viruses in the wheat plant itself. And although genetically engineered wheat is not an option in the market today, their research is building this resistance in non-genetically engineered wheat lines as well.

"(Wheat viruses) are a serious problem," Trick said. "Wheat streak mosaic virus is one of the most devastating viruses we have. It's prevalent this year. In addition to that, we have several other diseases, triticum mosaic virus and soil-borne mosaic virus, that are serious diseases."

Knowing how costly these diseases can be for producers, Fellers has worked on finding solutions for resistance throughout his career. As a doctoral student at the University of Kentucky, he used a technology in his research called pathogen-derived resistance, or RNA-mediated resistance -- a process that requires putting a piece of a virus into a plant to make it resistant to that particular virus. Most of the viruses that infect wheat are RNA viruses, he said.

"The plant has its own biological defense system," Fellers said. "We were just triggering that with this technology."

Now Fellers, with the help of Trick, his wheat transformation facility and K-State graduate students, have developed transgenic wheat lines that contain small pieces of wheat streak mosaic virus and triticum mosaic virus RNA.

"It's kind of like forming a hairpin of RNA," Fellers said. "What happens is the plant recognizes this RNA isn't right, so it clips a piece of it and chops it up, but then it keeps a copy for itself. Then we have a resistance element."

Fellers compared the process to the old days of viewing most wanted posters on the post office wall. The piece of foreign RNA from the virus, which is a parasite, is one of those most wanted posters. Because the virus is a parasite, it has to seize or hijack part of the plant system to make proteins that it needs to replicate.

When the virus comes into the plant, the plant holds up that poster from the post office wall, recognizes the virus, and doesn't allow the virus to replicate and go through its lifecycle.

A broad resistance goal

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Helping wheat defend itself against damaging viruses