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11/24/98

Contacts:
W. Allen Miller, Plant Pathology, (515) 294-2436
Barbara McManus, Agriculture Information, (515) 294-0707

ISU RESEARCHER DEVELOPS OAT PLANT RESISTANT TO VIRUS

AMES -- A team led by an Iowa State University molecular virologist has developed the first genetically engineered oat plants with resistance to barley yellow dwarf virus (BYDV). The work was published recently in the journal Phytopathology.

"This is the first published report of true transgenic resistance to BYDV in any crop," said developer W. Allen Miller, ISU plant pathology professor. "If this works in oats, the same gene should work in wheat and barley."

Despite its name, barley yellow dwarf virus is a serious pathogen of wheat, oats and barley. A gene from the virus was spliced into the plant's DNA by collaborator David Somers, University of Minnesota professor of agronomy and plant genetics. This does not harm the plant and actually makes the plant resistant to the virus.

The virus is transmitted to oat plants by aphids and is currently controlled by planting tolerant oat varieties for commercial production or by using insecticides to control the spread of the virus. Transgenic resistance will reduce the need for insecticides. BYDV is one of the most widespread and economically damaging viruses to small grain crops. Researchers estimate the virus can cause up to a 25-percent drop in yields.

Ken Frey, ISU agronomy professor emeritus, has followed research to develop resistant plants since the 1950s. Most of the research to develop resistant varieties has been done in the United States but the virus is found worldwide.

"This virus seems to be a pandemic type of disease; it's all over the world," Frey said. "It's not something that just occurs in the Corn Belt."

The new development allows scientists to expand research to more plant varieties.

"The popular varieties that are grown have been selected because of tolerance and that limits researchers," Miller said. "This will free them to use more genotypes. They won't be limited to using just the plants that are naturally tolerant to BYDV."

The recent gene transfer achievement came 10 years after Miller determined the sequences of all of the virus' genes while working as a postdoctoral scientist in Australia.

"That was a real landmark because no one knew much about this virus genetically or molecularly," Miller said. "It was the first time anyone had any idea about the sequence of a virus in what is called the luteovirus family. From a molecular biologist's viewpoint it helped us identify the viral genes that could be introduced into the plant's DNA to confer virus resistance."

The virus resistant gene can be introduced into wheat, barley and other cereal grains. Miller said the use of the gene in those crops could cut yield losses due to BYDV. High estimates indicate that up to 17 percent of the wheat crop and 15 percent of the barley crop can be lost to BYDV.

Field trial tests and additional breeding still need to be conducted before the BYDV resistant oat varieties are available commercially. Miller estimates it will be a few years before transgenic seed is available to producers.

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