Pm57 from Aegilops searsii encodes a novel tandem kinase protein conferring powdery mildew resistance in bread wheat

Abstract Powdery mildew is a devastating disease that affects wheat yield and quality. Despite wheat wild relatives being a valuable source of resistance genes, their incorporation into wheat improvement is constrained by their adverse effects on agronomic traits, difficulty in isolating genes and poor understanding of the resistance mechanisms. Here, we report cloning of Pm57, the first gene isolated from Aegilops searsii. It encodes an unusual wheat tandem kinase (WTK) protein with putative kinase-pseudokinase domains followed by a von Willebrand factor A (vWA) domain, designated WTK7-vWA. The resistance function of Pm57 was validated by independent mutants, gene silencing, and transgenic assays. Stable Pm57 transgenic wheat lines showed high levels and all-stage resistance against diverse isolates of Bgt fungus with no adverse effects on agronomic traits. Our findings highlight the emerging role of kinase fusion proteins in plant disease resistance and provide a powerful gene for wheat breeding.