By MATTHEW WEAVER

Capital Press

Resistance genes from heirloom wheat varieties might help the battle against the rust pathogen Ug99.

UG99 is devastating Southern Africa and Middle Eastern wheat production and is expected to invade Pakistan and the Indian subcontinent, but has yet to arrive in the United States.

Many existing wheat varieties are vulnerable to the rust. The resistance genes will help scientists develop varieties that fend off the rust.

USDA researchers are now testing genes to verify their Ug99 resistance.

"There are relatively few genes effective against Ug99," said Mike Bonman, USDA Agricultural Research Service plant pathologist in Aberdeen, Idaho. "It's important to give growers a lot of options: resistant varieties with multiple resistance genes in multiple backgrounds and varieties."

Heirloom races containing Ug99 resistance are from Chile, Ethiopia, Turkey, Herzegovina and Bosnia.

The next step is determining whether the resistance in those varieties is due to genes that haven't yet been identified. Bonman and researchers are making crosses to determine the location of the resistance genes in the wheat genome.

"If we have some that are previously unknown genes, then those would be the most valuable for resistance breeding," he said.

Funding for the project comes from the USDA Agricultural Research Service. Bonman said the National Small Grains Collection budget is about $990,000 per year, but roughly $150,000 per year is used to support the land races research, including salaries.

Screening is done in Kenya, in cooperation with the Kenya Agricultural Research Institute and the International Maize and Wheat Improvement Center. The Aberdeen location is also cooperating with the Cereal Disease Laboratory in St. Paul, Minn., where the fungus is kept quarantined, Bonman said.

Bonman is leading the land race, or heirloom, portion of the research. Others are monitoring the disease while others work to breed new varieties.

"We're trying to cover all the bases," he said. "There's no silver bullet. The solution to the problem is really multi-faceted, and this is one of the facets."

Bonman said resistance has been identified in spring wheat land races, and he expects to find out whether they are novel genes in three years.

Researchers are now turning to winter wheat land races, where resistance is more likely but screening is a little more challenging. He expects five to seven years of work with the winter varieties.