Wheat Gene With Resistance to Stripe Rust
An international team of researchers has discovered a gene that will make bread wheat capable of resisting stripe rust, a fungus that causes crop losses in many states.
Scientists transferred a resistant gene, known as Yr36, from a race of wild wheat into a handful of domesticated pasta and bread wheat varieties. The wild wheat was collected in Israel at the Fertile Crescent where ancient varieties of wheat have grown for centuries, says Ann Blechl, a geneticist at the USDA–Agricultural Research Service (ARS) Western Regional Research Center in Albany, Calif. Other scientists involved include Xianming Chen, a USDA–ARS plant pathologist in Pullman, Wash., and researchers from the University of California–Davis and the University of Haifa in Israel.
The researchers used a detailed map of a region of one wheat chromosome to isolate a candidate gene sequence into a susceptible bread wheat variety. Subsequent tests showed the transformed plants were resistant to at least eight races of stripe rust. Now breeders can use sequence-based DNA markers to incorporate the resistance into new and existing wheat varieties.
Wheat producers have been battling stripe rust in the Pacific Northwest since the 1950s, Chen says. Severe outbreaks occurred in the South and Midwest in 2000, and three years later the disease wiped out 25% of the wheat crop in California.
Caused by the fungus Puccinia striiformis, stripe rust is spread by the wind and is most likely to ruin crops in mild winters, wet springs and wet summers.
The fungus evolves rapidly, developing new races that overcome various race-specific seedling resistances. While Yr36 provides only partial resistance to adult plants at high temperatures, it is useful because it protects against all known strains of stripe rust.
Watch Wheat This Spring
Wheat insects are common, but they don't routinely cause economic disasters. That's both a blessing and a curse, says Phillip Sloderbeck, Kansas State University entomologist.
- March 2009