A unique wheat tandem kinase from wild emmer confers broad-spectrum resistance to powdery mildew. Triticum aestivum

Crop wild relatives offer novel natural variations of disease-resistance for crop improvement. Here, we isolated the broad-spectrum powdery mildew resistance gene Pm36, originating from wild emmer wheat through combination of PacBio SMRT long-read genome sequencing and map-based cloning. It encodes a unique tandem kinase with a transmembrane domain in the C-terminus, named as WTK-TM. Mutagenesis assay revealed that the two kinase domains (Kin I and Kin II) and the transmembrane domain of WTK-TM are all critical for its powdery mildew resistance function. Consistently, in vitro phosphorylation assay showed that both Kin I and Kin II are indispensable for the kinase activity of WTK-TM. Haplotype analysis uncovered that Pm36 is an orphan gene only present in a few wild emmer wheat populations, indicating its single ancient origin and potential contribution to current wheat gene pool. Overall, our findings not only provide a novel powdery mildew resistance gene with great potential in wheat breeding, but also sheds new lights into the mechanism of wheat tandem proteins underlying broad-spectrum resistance in wheat.