Hiebert, Colin W.Moscou, Matthew J.Hewitt, TimSteuernagel, BurkhardGreen, PhonZhang, PengPujol, VincentRouse, MatthewJin, YueMcIntosh, Robert A.Upadhyaya, Narayana M2023-04-052023-04-052041-1723http://hdl.handle.net/1885/288108Stem rust is an important disease of wheat that can be controlled using resistance genes. The gene SuSr-D1 identified in cultivar 'Canthatch' suppresses stem rust resistance. SuSr-D1 mutants are resistant to several races of stem rust that are virulent on wild-type plants. Here we identify SuSr-D1 by sequencing flow-sorted chromosomes, mutagenesis, and map-based cloning. The gene encodes Med15, a subunit of the Mediator Complex, a conserved protein complex in eukaryotes that regulates expression of protein-coding genes. Nonsense mutations in Med15b.D result in expression of stem rust resistance. Time-course RNAseq analysis show a significant reduction or complete loss of differential gene expression at 24 h post inoculation in med15b.D mutants, suggesting that transcriptional reprogramming at this time point is not required for immunity to stem rust. Suppression is a common phenomenon and this study provides novel insight into suppression of rust resistance in wheat.This work was supported in part by funds provided through Agriculture and Agri-Food Canada, Western Grains Research Foundation, Biotechnology and Biological Sciences Research Council (BB/P012574/1, BB/P016855/1), National Science Foundation (NSF BREAD program IOS-0965429), CSIRO, Gatsby Foundation, and the ERDF project “Plants as a tool for sustainable global development” (No. CZ.02.1.01/0.0/0.0/16_019/ 0000827). We thank Peter Dodds and Jeff Ellis for critical review of the manuscript prior to submission. We acknowledge the technical expertize of M. Popovic, G. Mardli, D. Edwards, T. Malasiuk, T. Zegeye, Z. Dubská, J. Weiserová, R. Šperková, W. Schnippenkoetter, and S. Chandramohan. We thank D. Klindworth and S. Xu for providing seed of mutant lines developed at the USDA (Fargo, North Dakota).application/pdfen-AU© 2020 The authorshttp://creativecommons.org/licenses/by/4.0/202010.1038/s41467-020-14937-22022-01-23Creative Commons Attribution licence