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

Colin W Hiebert, Matthew J Moscou, Tim Hewitt, Burkhard Steuernagel, Inmaculada Hernandez-Pinzon Toscano, Phon Green, Vincent Pujol, Peng Zhang, Matthew N Rouse, Yue Jin, Robert A McIntosh, Narayana Upadhyaya, Jianping Zhang, Sridhar Bhavani, Jan Vrána, Miroslava Karafiátová, Li Huang, Tom Fetch, Jaroslav Doležel, Brande B H WulffEvans Lagudah, Wolfgang Spielmeyer

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Abstract

Stem 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 24h 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. Stem rust is an important disease of wheat and resistance present in some cultivars can be suppressed by the SuSr-D1 locus. Here the authors show that SuSr-D1 encodes a subunit of the Mediator Complex and that nonsense mutations are sufficient to abolish suppression and confer stem rust resistance.

Original languageEnglish
Article number1123
Number of pages10
JournalNature Communications
Volume11
Issue number1
DOIs
Publication statusPublished - 28 Feb 2020

Keywords

  • F-SP TRITICI
  • AEGILOPS-TAUSCHII COSS.
  • DEFENSE GENE-EXPRESSION
  • LEAF RUST
  • HEXAPLOID WHEAT
  • COMMON WHEAT
  • PHYLOGENETIC ANALYSIS
  • STRIPE RUST
  • AESTIVUM L
  • RACE TTKS

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