Figure: For the first time ever, scientists are gaining ground in the race against wheat stem rust, a pathogen that threatens global food security because of its ability to kill wheat (MINNEAPOLIS/ST. PAUL 12/21/2017).

A team of researchers from the University of Sydney, Commonwealth Scientific and Industrial Research Organization (CSIRO) in Australia, Rothamsted Research in the United Kingdom, and the University of Minnesota and U.S. Department of Agriculture in the United States has discovered the first rust virulence molecule that wheat plants detect to ‘switch on' built-in resistance and stave off the disease.

Stem rust is the most dangerous pathogen of wheat, caused by the fungus Puccinia graminis f. sp. tritici (Pgt). Ug99, a particularly destructive form of Pgt, has recently received much attention because of its spread across Africa and the Middle East. The findings by this group of scientists published in Science reveal how the immune system in plants resistant to this disease directly recognizes a specific fungal protein to subsequently "turn on" resistance and fend off the pathogen.

Through this research, it will be possible to do DNA testing to identify whether a rust in a wheat crop anywhere in the world can overcome a rust-resistance gene, called Sr50. "Now that we've identified how stem rust strains are able to overcome Sr50 resistance – by mutation of a gene we've identified called AvrSr50 – this information can be used to help prioritize resistance genes for deployment," said University of Minnesota Plant Pathology Adjunct Professor Peter Dodds from CSIRO.

For more details about this research, read the news release from the University of Minnesota.