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United States Department of Agriculture

Agricultural Research Service

Ug99- emerging virulent stem rust races
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  In the News (provided on the BGRI website)
3/31/2011 Saving the world a grain at a time (MN Daily)
3/29/2011 Ug99 - an educational video (BGRI)
6/2/2010 Wheat rust tracking site launched (FAO)
2/22/2010 Red Menace: Stop the Ug99 Fungus Before Its Spores Bring Starvation  (Wired Magazine)
10/14/2008 Report for the stem rust surveillance and management workshop held July 30-31, 2008
7/2/2008 Ug99 Workshop Summary   Summary of national workshop on new virulences in wheat and barley stem rust held March 5-6, 2008, in Baltimore, Maryland.
4/2/2008 Gates Foundation awards $26.8 million to combat Ug99.
11/02/2007 Forum-Once Again, International Cooperation Key to Saving Wheat and Barley
1/02/2007 World Wheat Supply Threatened!
1/16/2007 Dangerous wheat disease jumps Red Sea - Devastating fungal pathogen spreads from eastern Africa to Yemen, following path scientists predicted.
3/30/2007 Deadly Wheat Fungus Threatens World's Breadbaskets(Science 30:1786-1787)





An emerging virulent stem rust race and vulnerability of wheat in the U.S. and worldwide.

New virulence in East Africa

In a nursery in Uganda, Africa in 1999, susceptible type stem rust pustules (collection designated Ug99) were found on wheat lines known to have the stem rust resistance gene Sr31, a gene for which no virulence had been reported previously anywhere in the world.  Similar virulence was observed in 2001 in Kenya and 2003 in Ethiopia.   (Race identification of earlier observations prior to 2001 could not be confirmed because of a lack of samples).   Race typing (race TTKS based on Pgt system of nomenclature, see Phytopathology 78:526-533) and DNA confirmed the presence in Kenya in 2005.  Sr31is on the 1B/1R chromosomal translocation, a piece of rye chromosome that has been introduced into many wheat cultivars.  In addtion to Sr31, the leaf rust resistance gene Lr26 and the stripe rust resistance gene Yr9are also on the 1B/1R translocation.

Stem rust vulnerability of wheat worldwide--the Sr31 factor

Stem rust resistance gene Sr31 is widely utilized in wheat worldwide, particularly in the India subcontinent, China, Europe, and South America.  From the CIMMYT report: Impacts of International Wheat Breeding Research in Developing Countries, 1966-97, developing countries planted 69 million hectares (~170 million acres) of spring wheat in 1997, of which nearly 80% were planted to CIMMYT-related varieties.   Susceptibility of this material will provide little barrier to the spread of a virulent race (e.g. TTKS).






 Current research emphasis

  • Screening U.S. wheat in Kenya against stem rust race TTKS

  • Characterizing sources of resistance

  • Mapping effective resistance genes




Germplasm evaluation


Last Modified: 8/30/2016
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