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ARS Home » Midwest Area » St. Paul, Minnesota » Cereal Disease Lab » Research » Publications at this Location » Publication #371775

Research Project: Cereal Rust: Pathogen Biology and Host Resistance

Location: Cereal Disease Lab

Title: Stem rust resistance in wheat is suppressed by a subunit of the mediator complex

Author
item HIEBERT, COLIN - Agriculture And Agri-Food Canada
item MOSCOU, MATTHEW - Sainsbury Laboratory
item HEWITT, TIMOTHY - University Of Sydney
item STEUERNAGEL, BURKHARD - John Innes Center
item HERNANDEZ-PINZON, INMACULADA - Sainsbury Laboratory
item GREEN, PHON - Sainsbury Laboratory
item PUJOL, VINCENT - The Australian National University
item ZHANG, PENG - University Of Sydney
item Rouse, Matthew
item Jin, Yue
item MCINTOSH, ROBERT - University Of Sydney
item UPADHYAYA, NARAYANA - Commonwealth Scientific And Industrial Research Organisation (CSIRO)
item ZHANG, JIANPING - Commonwealth Scientific And Industrial Research Organisation (CSIRO)
item BHAVANI, SRIDHAR - International Maize & Wheat Improvement Center (CIMMYT)
item VRANA, JAN - Institute Of Experimental Botany
item KARAFIATOVA, MIROSLAVA - Institute Of Experimental Botany
item HUANG, LI - Montana State University
item FETCH, THOMAS - Agriculture And Agri-Food Canada
item DOLEZEL, JAROSLAV - Institute Of Experimental Botany
item WULFF, BRANDE - John Innes Center
item LAGUDAH, EVANS - Commonwealth Scientific And Industrial Research Organisation (CSIRO)
item SPIELMEYER, WOLFGANG - Commonwealth Scientific And Industrial Research Organisation (CSIRO)

Submitted to: Nature Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/11/2020
Publication Date: 2/28/2020
Citation: Hiebert, C.W., Moscou, M.J., Hewitt, T., Steuernagel, B., Hernandez-Pinzon, I., Green, P., Pujol, V., Zhang, P., Rouse, M.N., Jin, Y., McIntosh, R.A., Upadhyaya, N.M., Zhang, J., Bhavani, S., Vrana, J., Karafiatova, M., Huang, L., Fetch, T.G., Dolezel, J., Wulff, B.B., Lagudah, E.S., Spielmeyer, W. 2020. Stem rust resistance in wheat is suppressed by a subunit of the mediator complex. Nature Communications. 11(1123). https://doi.org/10.1038/s41467-020-14937-2.
DOI: https://doi.org/10.1038/s41467-020-14937-2

Interpretive Summary: Stem rust (Puccinia graminis f. sp. tritici) is an important fungal disease of wheat that can be controlled by developing cultivars that carry effective resistance genes. The wild-type form of gene SuSr-D1 identified in the cultivar 'Canthatch' suppresses stem rust resistance. SuSr-D1 mutants are resistant to several races of the stem rust fungus that are virulent on wild-type plants. Sequencing flow-sorted chromosomes from wild-type and mutant lines facilitated the isolation of SuSr-D1 through linkage and physical mapping. The gene was predicted to encode Med15, a subunit of the Mediator Complex, a conserved protein complex that regulates the expression of protein-coding genes in eukaryotes. Seven independent nonsense mutations in Med15b.D resulted in the expression of race-specific stem rust resistance. Suppression is a common phenomenon when transferring resistance genes from progenitor species to wheat and limits the reservoir of resistance genes available for sustainable wheat improvement. This study provides novel insight into suppression of rust resistance in wheat. The mutants of the suppressor gene could be used to breed wheat cultivars with improved resistance to stem rust. Resistant wheat cultivars protect U.S. wheat production from the threat of foreign virulent races of the stem rust pathogen.

Technical Abstract: Stem rust (Puccinia graminis f. sp. tritici) is an important fungal disease of wheat that can be controlled by developing cultivars that carry effective resistance genes. The wild-type form of gene SuSr-D1 identified in the cultivar 'Canthatch' suppresses stem rust resistance. SuSr-D1 mutants are resistant to several races of the stem rust fungus that are virulent on wild-type plants. Sequencing flow-sorted chromosomes from wild-type and mutant lines identified EMS-induced SNVs that facilitated the isolation of SuSr-D1 through linkage and physical mapping. The gene was predicted to encode Med15, a subunit of the Mediator Complex, a conserved protein complex that regulates the expression of protein-coding genes in eukaryotes. Seven independent nonsense mutations in Med15b.D resulted in the expression of race-specific stem rust resistance. Time-course RNAseq analysis found a significant reduction or complete loss of differential gene expression at 24 hours 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 when transferring resistance genes from progenitor species to wheat and limits the reservoir of resistance genes available for sustainable wheat improvement. This study provides novel insight into suppression of rust resistance in wheat.