Scientists discover gene for wheat resistance to Ug99
The world's food supply should be a little more plentiful thanks to a scientific breakthrough, according to excited university wheat researchers.
Eduard Akhunov, associate professor of plant pathology at Kansas State University, and his colleague, Jorge Dubcovsky from the University of California-Davis, led a research project that identified a gene that gives wheat plants resistance to one of the most deadly races of the wheat stem rust pathogen Ug99. This rust was first discovered in Uganda in 1999.
The discovery may help scientists develop new wheat varieties and strategies that protect the world's food crops against the wheat stem rust pathogen that is spreading from Africa to the breadbaskets of Asia and can cause significant crop losses.
Other Kansas State University researchers include Harold Trick, professor of plant pathology; Andres Salcedo, doctoral candidate in genetics from Mexico; and Cyrille Saintenac, a postdoctoral research associate currently working at the Institut National de la Recherche Agronomique in France. The project was funded by the U.S. Department of Agriculture and Borlaug Global Rust Initiative.
The team's study, "Identification of Wheat Gene Sr35 that Confers Resistance to Ug99 Stem Rust Race Group," appears in the journal Science.
It identifies the stem rust resistance gene named Sr35, and appears alongside a study from an Australian group that identifies another effective resistance gene called Sr33.
"This gene, Sr35, functions as a key component of plants' immune system," Akhunov said. "It recognizes the invading pathogen and triggers a response in the plant to fight the disease."
Wheat stem rust is caused by a fungal pathogen. According to Akhunov, since the 1950s wheat breeders have been able to develop wheat varieties that are largely resistant to this pathogen. However, the emergence of strain Ug99 in Uganda in 1999 devastated crops and has spread to Kenya, Ethiopia, Sudan and Yemen, though has yet to reach the U.S.
"Until that point, wheat breeders had two or three genes that were so efficient against stem rust for decades that this disease wasn't the biggest concern," Akhunov said. "However, the discovery of the Ug99 race of pathogen showed that changes in the virulence of existing pathogen races can become a huge problem."
As a first line of defense, wheat breeders and researchers began looking for resistance genes among those that had already been discovered in the existing germplasm repositories, he said.