Agriculture and Agri-Food Canada, Morden Research and Development Centre, 101 Route 100, Morden, MB, R6M 1Y5, Canada.
The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich, NR4 7UK, UK.
Nat Commun. 2020 Feb 28;11(1):1123. doi: 10.1038/s41467-020-14937-2.
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 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.
秆锈病是一种重要的小麦病害，可以通过抗性基因进行控制。在品种“Canthatch”中鉴定出的基因 SuSr-D1 抑制秆锈病抗性。SuSr-D1 突变体对几种野生型植物上毒性很强的秆锈菌具有抗性。在这里，我们通过测序流式分选染色体、诱变和基于图谱的克隆来鉴定 SuSr-D1。该基因编码 Mediator Complex 的一个亚基 Med15，Mediator Complex 是真核生物中一种保守的蛋白质复合物，调节蛋白质编码基因的表达。Med15b.D 中的无义突变导致秆锈病抗性表达。时间进程 RNAseq 分析显示，在 24 小时后接种时，med15b.D 突变体中的差异基因表达显著减少或完全丧失，表明此时的转录重编程不是对秆锈病免疫所必需的。抑制是一种常见现象，本研究为小麦锈病抗性抑制提供了新的见解。
