Miller Magazine Issue: 131 November 2020

34 NEWS MILLER / November 2020 A team of scientists representing the USDA's Agricultural Research Service in Manhattan, Kansas State University and other universities has been recognized for pioneering work in building durable resistance to Ug99, a highly-virulent strain of stem rust in wheat. K-State scientists earn award for pioneering work with wheat genes Two U.S. Department of Agriculture scientists wor- king on the Kansas State University campus are part of a national team that has earned praise for its pionee- ring work in building sturdy resistance to a highly-vi- rulent strain of stem rust in wheat. The Borlaug Global Rust Initiative awarded its 2020 Gene Stewardship award to a USDA Agricultural Re- search Service team that includes Robert Bowden and Mary Guttieri, who are adjunct faculty at K-State, and colleagues from four other states. “When it comes to stem rust and breeding stem rust resistant wheat, this is the go-to team and the undis- puted leader for the United States,” said Jose Costa, national program leader for grain crops at USDA-ARS, in a press release announcing the award. “For years, the entire wheat community has relied on their lea- dership, scientific skills and contributions to cultivar development and screening for resistance to rust dise- ases. Their evaluation of materials in Africa and at the USDA facility in Minnesota is literally the only thing that stands between the American wheat producer and catastrophe should the disease – which is spread by airborne spores and jet streams – come to the Uni- ted States.” Bowden, supervisory plant pathologist with the ARS Hard Winter Wheat Genetics Research unit in Man- hattan, said the group’s success hinges on stacking genes resistant to Ug99, a stem rust that has wreaked havoc in parts of Africa since the late 1990s, and other parts of the world since then. “Gene stewardship is taking care of genes so they will be useful in the future, in addition to their useful- ness now,” Bowden said. “We’ve had a lot of resis- tance genes over the years and we tend to put them out one at a time. But the pathogen (stem rust) can actually mutate and defeat the resistance gene.” Wheat scientists at K-State have been successful in locating molecular markers in resistance genes that al- low them to stack the genes one on top of the other and form a pyramid that is more durable to stem rust’s attempts to beat the resistance. “It’s very difficult to stack the genes,” Bowden said. “But when you are able to stack them, they protect each other. The pro- bability of defeating one gene is a certain number – let’s say one in a million. So then, the probability of defeating two genes is one in a million times one in a million. “When you stack them up, it becomes less and less probable that the pathogen is going to be able to mutate and defeat all of the genes in this deck. So if you want a gene to last a long time, you put it in a stack. Even if the pathogen defeats one, it doesn’t defeat the rest.” Since 2006, the USDA-ARS team has evaluated more than 20,000 germplasm accessions for genes as- sociated with resistance to Ug99 and other stem rust races. So far, they have discovered 20 resistance genes effective against Ug99 and have published more than 140 journal articles.