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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 Title: Resistance to race TTKSK of Puccinia graminis f. sp. tritici in Emmer Wheat (Triticum turgidum ssp. dicoccum)

Authors
item Olivera, Pablo -
item Babebo, A -
item Xu, Steven
item Klindworth, Daryl
item Jin, Yue

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 2012
Publication Date: April 1, 2012
Citation: Olivera, P., Babebo, A., Xu, S.S., Klindworth, D.L., Jin, Y. 2012. Resistance to race TTKSK of Puccinia graminis f. sp. tritici in Emmer Wheat (Triticum turgidum ssp. dicoccum). Crop Science. 125:817–824.

Interpretive Summary: Emmer wheat, a ancient hulled wheat, is known to be a source of resistance to stem rust. This wheat has not been tested against race TTKSK (or Ug99), an emerging stem rust race originated in eastern Africa. The objective of this research was to identify and characterize stem rust resistance effective against race TTKSK and other races with broad virulence. Based on laboratory and field studies, high frequency of emmer wheat deposited in the US wheat collection were found to be resistant to TTKSK. Studies were conducted to determine the inheritance of TTKSK resistance in five selected resistant accessions and resulted in the discovery of effective resistance genes. Results from this study indicated that emmer wheat is a rich source of resistance to race TTKSK, and may contribute novel stem rust resistance genes. Since emmer wheat shares the same genome as durum wheat and is in cultivated form, resistance genes should be easily transferred to durum wheat by conventional breeding approaches. This research will help scientists in understanding the genetic diversity of stem rust resistance and will help breeders in developing stem rust cultivars in wheat.

Technical Abstract: Race TTKSK (Ug99) of Puccinia graminis f. sp. tritici is a serious threat to wheat production worldwide because of its wide virulence on many cultivars and rapid spread in eastern Africa and southwestern Asia. Emmer wheat (Triticum turgidum ssp. dicoccum) is known to be a source of resistance to stem rust, but has not been evaluated against race TTKSK. In attempts to identify and characterize stem rust resistance genes effective against race TTKSK at the seedling stage, we evaluated 359 accessions of emmer wheat with race TTKSK and other races with broad virulence. A high frequency (31.8%) of accessions were resistant to TTKSK at the seedling stage with low infection types ranging from 2= to 2+. Thirty-seven accessions exhibited a resistant to moderately resistant response in Debre Zeit, Ethiopia and St. Paul, MN nurseries in 2010 and 2011. Studies were conducted to determine the inheritance of TTKSK resistance in five accessions at the seedling stage. Results from evaluating F2 and F2:3 generations derived from resistant × susceptible crosses revealed that resistance was conferred by single genes. One additional resistance gene effective against race TTTTF was identified in all the resistant parents. Results from this study indicated that emmer wheat is a rich source of resistance to race TTKSK, and may contribute novel stem rust resistance genes. Since emmer wheat shares the same genome as durum wheat and is in cultivated form, resistance genes should be easily transferred to durum wheat by conventional breeding approaches.

Last Modified: 11/27/2014