Mutant fungus Ug99 threatens world crops and even political stability.

 Jim Gehrz, Star Tribune - Some wheat plants are grown under controlled conditions in a greenhouse at the Cereal Disease Laboratory at the U of M. Jim Anderson is pictured.
Jim Gehrz, Star Tribune - Some wheat plants are grown under controlled conditions in a greenhouse at the Cereal Disease Laboratory at the U of M. Jim Anderson is pictured.

The battlefields are 8,000 miles away in Africa and the Middle East. But from their bunkers of dew chambers and greenhouses in St. Paul, a strike force of University of Minnesota plant experts is devising strategies to win a high-stakes war that could prevent famine, starvation and political unrest.

The enemy, Puccinia graminis, is a new mutant strain of fungus that erupts from pockmarks on the stems of wheat and barley, exploding with millions of rusty red spores that can blow across continents. Nicknamed Ug99 after it was discovered in Uganda in 1999, this new race of stem rust is the rabbit of cereal grain pathogens — creating new generations of spores in a matter of weeks. It has crippled wheat farms in East Africa and jumped across the Red Sea to Yemen and Iran.

“This fungus has such a tremendously explosive reproductive capacity,” said Brian Steffenson, a plant pathology professor at the U who travels regularly to the Ug99 front lines in Kenya. “By way of the prevailing winds, we’re now afraid that if Ug99 gets a beachhead in the Middle East, it can spread to the breadbaskets of south Asia, Pakistan and India.

“That,” he said, “would be absolutely devastating for the world’s wheat and economy.”

Eighty percent of the world’s wheat and 95 percent of the Upper Midwest region’s top bread-baking grain is vulnerable to the new pathogen, according to University of Minnesota wheat breeder Jim Anderson.

“The stem rust fungus, like various flu strains that attack humans, is capable of mutating and overcoming the resistance of previously resistant cereal crops,” Steffenson said. “The 800-pound gorilla in the room is whether Ug99 will ever make its way to the western hemisphere and into our region.”

Anderson thinks it’s “a matter of when, rather than if” the new rust finds its way to the Red River Valley and other North American wheat fields, prompting a scramble among scientists to cross new varieties of wheat genes that can resist the scourge.

Agricultural authorities are so jittery about Ug99 infecting U.S. wheat, they allow only two labs in the country to experiment with the fungus. And both the U.S. Department of Agriculture’s Cereal Disease Lab and the U’s adjacent containment facility are tucked quietly on the agriculture campus in St. Paul.

To conduct his research in the containment facility in St. Paul, Steffenson walks through a series of seven security doors, removes his clothes and dons a special suit to prevent spreading the pathogen. Just in case a spore accidentally got loose in Minnesota, the government requires all Ug99 research to happen in the winter months when the pathogen would die in the cold. When Steffenson travels to East Africa, ground zero for Ug99, he leaves a set of field clothing and pairs of his size 15 shoes in Kenya to reduce the risk of accidentally importing the fungus.

“Other diseases might nibble at a little bit of yield here and a bit of quality there, but this stem rust pathogen is a real game changer,” Steffenson said. “So we’ve really shifted into high gear to thwart it.”

As in any battle, dire developments duel with positive advances:

•In 2008, after a decade of genetic dabbling, Anderson released a variety of wheat he named Tom, which now grows on nearly 2 percent of Minnesota’s wheat acreage and shows good resistance to Ug99 in the lab.

•The Gates Foundation has funneled $26.8 million, through Cornell University, to help bankroll the research. A portion of that money is going to St. Paul-based plant scientists working on Ug99.

•Fungicides can control the new rust, although affording the chemical sprays is daunting for small-scale farmers in Africa and Asia.

“And we have not had any major epidemics in this region since the 1950s,” Steffenson said. “That’s a huge success story.”

A history at the vortex

It’s no coincidence that one of the world’s leading grain disease think-tanks has kept the upper hand on the region’s plant pathogens for decades.

Not far from the Minnesota State Fair water tower, Steffenson stood on the back of a tractor the other day, orchestrating the planting of barley seeds that will grow into part of his Ug99 research. Minnesotans have long been at the crux of crop rust research. Norman Borlaug, who died last September at 95, earned a Ph.D. at the University of Minnesota in 1942 and a Nobel Peace Prize in 1970 for developing high-yield, disease-resistant wheat credited with saving a billion people in Asia from starvation in the 1960s.

Rust epidemics in 1916, the mid-’30s and early-’50s devastated Minnesota milling, a cornerstone of the state’s early economy, and damaged other sectors, such as railroads that lost profit when grain cars sat empty. That prompted the Legislature to pour money into the research facilities on the farm campus, where Minnesotans remain at the forefront.

Steffenson and Anderson grew up in Anoka and St. Peter, respectively. And the new resistant variety Tom is named after Tom Anderson, a grain research advocate from Sabin, Minn., who died in 2007.

Despite all the Minnesota connections, rust research is an international game. To wit: Yue Jin, the USDA’s top wheat expert in St. Paul, grew up on a farm in Inner Mongolia, and Steffenson recently hosted Russian and Italian scientists, who can’t work with Ug99 in their countries.

Their battle is nothing new. Centuries ago, Romans held an annual festival around this time of year just as rust would have taken hold on grain stems in Italy. They would sacrifice a dog and sheep and pray to the rust god to leave their crops alone.

“Scaly Robigo, god of rust, spare Ceres’ grain,” the ancient Roman poet Ovid wrote. “Let silky blades quiver on the soil’s skin … and keep scabrous hands from the harvest.”

Since those days of yore, the rust fungi have periodically flared up, mutating into new resistance-proof strains that choke the grains’ nutrients and growth. Ug99 is simply the latest scourge to plague wheat and barley growers.

“With some other rusts, you might see yield losses of 10 percent or 40 percent in a worst-case scenario,” Anderson said. “This new stem rust can virtually wipe out a crop.”

So the scientists juggle the need to crossbreed grains that are not only resistant to disease, but grow well enough to give farmers good yields for milling and baking.

The stakes couldn’t be higher. Riots broke out in Eygpt two years ago when low wheat stocks triggered soaring prices and food shortages. Scientific models predict Ug99 will strike in the Punjab valley, a vital wheat-growing region that straddles India and Pakistan.

“If it gets there, there could be massive starvation and political instability,” said Les Szabo, a USDA research geneticist in St. Paul and one of more than two dozen local scientists battling Ug99.

Some of the experts have dissected the DNA sequence in the pathogen’s genome. Others focus on the host or secrets that might be locked in wild grain species. As they continue to cross genes and screen for resistance, Steffenson said both the research and the threat offer a valuable reminder.

“The pathogen is vying against those of us working with disease resistance, kind of like an arms race with one thwarting the other, as in any battle,” Steffenson said. “Many Americans take food for granted because they can easily get what they want from the grocery store. They seem to forget that food comes from crops sown in the fields where diseases have been plaguing man for centuries.”