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Defending the global breadbasket

June 8, 2011


Norman Borlaug.

University of Minnesota alumnus Norman Borlaug bred lines of high-yielding wheat credited with preventing starvation in many parts of the world.

World's top experts on a deadly wheat fungus gather at the U

By Deane Morrison

It isn't enough that the University of Minnesota gave the world Norman Borlaug, the Nobel Peace Prize-winning wheat breeder credited with staving off starvation in many parts of the developing world.

Today, wheat faces a threat from wheat stem rust, a family of deadly fungi with the potential to wipe out 80 percent of the world's crop.

Researchers at the USDA's Cereal Disease Laboratory on the University's St. Paul campus are now fighting on the front lines of a worldwide battle against the fungus and will be featured at a major international gathering of some 400 like-minded scientists this week (June 13-16, 2011) in St. Paul.

Among the speakers is Les Szabo, from the Cereal Disease Laboratory (part of the USDA's Agricultural Research Service) and the U's Department of Plant Pathology.

Last month he and a team of researchers he co-led published the genome sequences of the wheat stem rust and poplar leaf rust fungal pathogens in the Proceedings of the National Academy of Sciences. These sequences provide a basis of reference that enables the study of genetic variation in these rust fungi.

This accomplishment laid the cornerstone for work to identify the proteins that allow rust fungi to infect plants and other proteins that allow some plants to resist them. Also, in an ongoing project, the Gates Foundation has funded Szabo and his colleagues to sequence the genome of a sample of Ug99, a particularly virulent strain of wheat stem rust.

Road map to resistance

Sequencing the wheat stem rust fungal genome is a vital first step to finding ways of breeding rust-resistant wheat, the best hope for defeating the fungus.

For example, when the genomes of two other wheat rust pathogens (wheat striped rust and wheat leaf rust) are sequenced, they can be compared to the wheat stem rust fungal genome and commonalities and differences noted. This will yield important information on what genes are required for these pathogens to infect wheat.

Knowing this can help the effort to breed resistance into wheat:

• With genes suspected of causing infection in hand, scientists can tell what the proteins produced from them must look like and search for them. The targets of the search are "effector proteins," small proteins that rusts secrete onto a wheat plant and that are suspected of helping defeat the plant's defenses.

• Once potential effector proteins are found, they can be isolated and applied, one by one, to susceptible wheat plants to see if any act like agents of infection. If so, they would be applied to a plant like rice—which is resistant to wheat rusts—and any rice genes that react to the attack identified.

• If any proteins produced from those rice genes are found to interact antagonistically with rust effector proteins, the genes could be engineered into susceptible wheat, which would then be tested for rust resistance. 

With wheat rust fungus constantly evolving new strains, it's a monumental task. But with the sequencing work by Szabo and his colleagues, the task has already begun.

"It gives everybody a toolbox," he says. "We now have a blueprint—it gives us information to start looking for specific [infection-related events] and start building countermeasures."

Szabo will deliver his talk, "Puccinia graminis: Variation is the Rule," at 3 p.m. Tuesday, June 14, in the Crowne Plaza Hotel in St. Paul.

The conference takes place at the hotel, except for Monday's (June 13) activities, which will be held on the University's St. Paul campus. Monday's events include a sneak preview of a Twin Cities Public Television film on the international impact of University of Minnesota researchers on wheat, and the battles against wheat diseases that continue to threaten wheat and cereal production; field tours of current research projects; and a ceremonial groundbreaking for an expanded Cereal Disease Laboratory.

 

Tags: College of Food, Agricultural and Natural Resource Sciences

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Related Links

Complete conference schedule

News release on sequencing project

Stalking a Cereal Killer (news feature)

A Tribute to Norman Borlaug (obituary)

Cereal Disease Laboratory

Department of Plant Pathology

College of Food, Agricultural and Natural Resource Sciences

Les Szabo