Researcher at Ug99 wheat stem rust screening nursery in Kenya.

MN Impact: U of M Researchers Help Uncover Ug99 Resistant Genes

June 22, 2017

Issue (Who cares and Why)

Ug99 is a lineage of wheat stem rust present in wheat fields in several countries in Africa and the Middle East. Due to its virulence to several stem rust resistance genes, it is predicted to spread rapidly through these regions and possibly further afield.

What has been done

In an effort to identify genes with resistance to Ug99, University researchers carried out a genome-wide association study on a panel of 250 spring wheat breeding lines from the International Maize and Wheat Improvement Center, six wheat breeding programs in the US, and three breeding programs in Canada.


Only nine of the 250 lines displayed seedling resistance to all three races. Twenty-seven SNP markers associated with APR against Ug99 were detected and 23, 86, and 111 SNP markers associated with seedling resistance against races TTKSK, TRTTF, and TKTTF respectively.

This study demonstrates that North American wheat breeding lines have several loci that provide APR and seedling resistance to highly virulent Pgt races. Using the resistance lines and the SNP markers identified in this study, marker-assisted resistance breeding can assist in the development of varieties with elevated levels of resistance to virulent stem rust races including TTKSK.

Infected wheat at UG99 wheat stem rust screening nursery in Kenya.

Infected wheat at UG99 wheat stem rust screening nursery, and farms near it, in Njoro, Kenya.