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ARS Home » Midwest Area » St. Paul, Minnesota » Cereal Disease Lab » Research » Publications at this Location » Publication #349458

Research Project: Cereal Rust: Pathogen Biology and Host Resistance

Location: Cereal Disease Lab

Title: Identification and characterization of wheat stem rust resistance gene Sr21 effective against the Ug99 race group at high temperature

Author
item Chen, Shisheng - University Of California, Davis
item Zhang, Wenjun - University Of California, Davis
item Bolus, Stephen - University Of California, Davis
item Rouse, Matthew - Matt
item Dubcovsky, Jorge - University Of California, Davis

Submitted to: PLoS Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/5/2018
Publication Date: 4/3/2018
Citation: Chen, S., Zhang, W., Bolus, S., Rouse, M.N., Dubcovsky, J. 2018. Identification and characterization of wheat stem rust resistance gene Sr21 effective against the Ug99 race group at high temperature. PLoS Genetics. 14(4):e1007287. https://doi.org/10.1371/journal.pgen.1007287.
DOI: https://doi.org/10.1371/journal.pgen.1007287

Interpretive Summary: Stem rust of wheat, caused by Puccinia graminis f. sp. tritici (Pgt), is a devastating foliar disease. The emerging Ug99 race group has combined virulence to most stem rust (Sr) resistance genes currently deployed in wheat and is a threat to global wheat production. Here we use map-based cloning to identify disease resistance gene sequence completely linked to the Ug99 resistant gene Sr21. Loss-of-function mutations and transgenic complementation confirmed that this gene is Sr21. Sr21 transcripts were significantly higher at high temperatures, and this was associated with significantly increased levels of resistance at those temperatures. Introgression of Sr21 into hexaploid wheat resulted in lower levels of resistance than in diploid wheat, but transgenic hexaploid wheat lines with high levels of Sr21 expression showed high levels of resistance. Our results suggest that Sr21 can be a valuable component of transgenic cassettes or gene pyramids combining multiple resistance genes against Ug99 and other virulent stem rust races. The discovery of the Sr21 gene sequence may facilitate the improvement of Ug99 resistance in United States wheat varieties. Ug99 resistant wheat varieties would protect United States wheat production from yield loss if a Ug99 epidemic were to occur in the United States.

Technical Abstract: Stem rust of wheat, caused by Puccinia graminis f. sp. tritici (Pgt), is a devastating foliar disease. The emerging Ug99 race group has combined virulence to most stem rust (Sr) resistance genes currently deployed in wheat and is a threat to global wheat production. Here we use map-based cloning to identify a coiled-coil, nucleotide-binding leucine-rich repeat protein (NLR) completely linked to the Ug99 resistant gene Sr21 from Triticum monococcum. Loss-of-function mutations and transgenic complementation confirmed that this gene is Sr21. Sr21 transcripts were significantly higher at high temperatures, and this was associated with significantly increased levels of resistance at those temperatures. Introgression of Sr21 into hexaploid wheat resulted in lower levels of resistance than in diploid wheat, but transgenic hexaploid wheat lines with high levels of Sr21 expression showed high levels of resistance. Our results suggest that Sr21 can be a valuable component of transgenic cassettes or gene pyramids combining multiple resistance genes against Ug99 and other virulent stem rust races.