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United States Department of Agriculture

Agricultural Research Service

Research Project: GENETICS, POPULATION BIOLOGY, AND HOST-PARASITE INTERACTIONS OF CEREAL RUST FUNGI AND THEIR DISEASES

Location: Cereal Disease Laboratory

Title: The emergence of Ug99 races of the stem rust fungus is a threat to world wheat production

Authors
item Singh, R -
item Hodson, D -
item Huerta-Espino, J -
item Jin, Yue
item Bhavani, S -
item Njau, P -
item Herreta-Foessel, S -
item Singh, P -
item Govindan, V -

Submitted to: Annual Review of Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 29, 2011
Publication Date: August 10, 2011
Citation: Singh, R., Hodson, D., Huerta-Espino, J., Jin, Y., Bhavani, S., Njau, P., Herreta-Foessel, S., Singh, P., Govindan, V. 2011. The emergence of Ug99 races of the stem rust fungus is a threat to world wheat production. Annual Review of Phytopathology. 49:465-481.

Interpretive Summary: Stem rust or black rust is a fungal disease of wheat and is caused by the fungus Puccinia graminis tritici. Race Ug99 of the stem rust pathogen was first detected in Uganda in 1998. Seven races or variants belonging to the Ug99 complex are now known and have spread to the wheat-growing countries of Zimbabwe, South Africa, Sudan, Yemen, and Iran in the eastern African highlands. Wheat varieties grown over 90% of the production area worldwide are susceptible to this complex of races. Thus, the Ug99 group of races was recognized as a major threat to wheat production and food security. Its spread, either wind-mediated or human-aided, to other countries in Africa, Asia, and beyond is likely. Screening in Kenya and Ethiopia has identified a low frequency of resistant wheat varieties and breeding materials. Identification and transfer of new sources of race-specific resistance from various wheat relatives is underway to enhance the diversity of resistance. Although new Ug99 resistant varieties that yield more than current popular varieties are being released and promoted, major efforts are required to displace current Ug99 susceptible varieties with varieties that have diverse race-specific or durable resistance and mitigate the Ug99 threat.

Technical Abstract: Race Ug99 of the fungus Puccinia graminis tritici that causes stem or black rust disease on wheat was first detected in Uganda in 1998. Seven races belonging to the Ug99 lineage are now known and have spread to the wheat-growing countries of Zimbabwe, South Africa, Sudan, Yemen, and Iran in the eastern African highlands. Because of the susceptibility of wheat varieties grown over 90% of the area worldwide, the Ug99 group of races was recognized as a major threat to wheat production and food security. Its spread, either wind-mediated or human-aided, to other countries in Africa, Asia, and beyond is evident. Screening in Kenya and Ethiopia has identified a low frequency of resistant wheat varieties and breeding materials. Identification and transfer of new sources of race-specific resistance from various wheat relatives is underway to enhance the diversity of resistance. Although new Ug99 resistant varieties that yield more than current popular varieties are being released and promoted, major efforts are required to displace current Ug99 susceptible varieties with varieties that have diverse race-specific or durable resistance and mitigate the Ug99 threat.

Last Modified: 7/31/2014
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