Wheat gene Sr60 encodes a protein with two putative kinase domains that confers resistance to stem rust

Authors: CHEN, SHISHENG - University Of California, Davis; Rouse, Matthew; ZHANG, WENJUN - University Of California, Davis; ZHANG, XIAOQIN - University Of California, Davis; GUO, YAN - University Of California, Davis; BRIGGS, JORDAN - University Of Minnesota; DUBCOVSKY, JORGE - University Of California, Davis

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2019
Publication Date: 9/5/2019
Citation: Chen, S., Rouse, M.N., Zhang, W., Zhang, X., Guo, Y., Briggs, J., Dubcovsky, J. 2019. Wheat gene Sr60 encodes a protein with two putative kinase domains that confers resistance to stem rust. New Phytologist. 225(2):948–959. https://doi.org/10.1111/nph.16169.
DOI: https://doi.org/10.1111/nph.16169

Interpretive Summary: Wheat stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is a devastating fungal disease threatening global wheat production. The rapid emergence of new virulent Pgt races has prompted global efforts to find and clone effective resistance genes. Here, we report the identification of stem rust resistance gene Sr60, a race-specific gene from diploid wheat Triticum monococcum that encodes a protein with two putative kinase domains that confers intermediate levels of resistance to Pgt. Transformation of Sr60 into the susceptible wheat variety Fielder was sufficient to confer resistance to stem rust. The Sr60 gene was only found in T. monococcum but not in cultivated wheat. We successfully developed a diagnostic molecular marker for Sr60 and introgressed a small T. monococcum segment containing this gene into hexaploid wheat to accelerate its deployment and pyramiding with other stem rust resistance genes in common wheat-breeding programs. The cloned Sr60 can be a useful component of transgenic cassettes including resistance genes with complementary resistance profiles. The Sr60 gene and markers can be used to develop wheat varieties in the U.S. with improved resistance to stem rust.

Technical Abstract: Wheat stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is a devastating fungal disease threatening global wheat production. The rapid emergence of new virulent Pgt races has prompted global efforts to find and clone effective resistance genes. Here, we report the identification of stem rust resistance gene Sr60, a race-specific gene from diploid wheat Triticum monococcum that encodes a protein with two putative kinase domains that confers intermediate levels of resistance to Pgt. Transformation of a ~10-kb genomic sequence carrying Sr60 into the susceptible wheat variety Fielder was sufficient to confer resistance to stem rust. Sr60 transcripts were significantly higher in Pgt-inoculated than mock-inoculated plants one day after inoculation. The transient transcriptional upregulation of Sr60 was reflected in the upregulation of several pathogenesis-related genes. The Sr60-resistant haplotype was only found in T. monococcum but not in cultivated wheat. We successfully developed a diagnostic molecular marker for Sr60 and introgressed a small T. monococcum segment containing this gene into hexaploid wheat to accelerate its deployment and pyramiding with other stem rust resistance genes in common wheat-breeding programs. The cloned Sr60 can be a useful component of transgenic cassettes including resistance genes with complementary resistance profiles.