An atypical NLR pair TdCNL1/TdCNL5 from wild emmer confers powdery mildew resistance in wheat

Abstract

Resistance to wheat powdery mildew is commonly mediated by individual resistance proteins, most of which encode nucleotide-binding leucine-rich repeat (NLR) receptors. Here we report that the powdery mildew resistance gene MLIW170/PM26 in wild emmer and bread wheat derivatives is determined by a genetically linked atypical NLR pair TdCNL1/TdCNL5. Map-based cloning and PacBio HiFi long-read sequencing revealed that TdCNL1 encodes an atypical coiled-coil-domain-containing NLR protein (CNL) fused with a new potassium-dependent sodium-calcium exchanger integrated domain, whereas TdCNL5 encodes a canonical CNL protein. Mutagenesis and virus-induced gene silencing experiments indicated that both TdCNL1 and TdCNL5 are essential for powdery mildew resistance. Transgenic plants with TdCNL1 alone or TdCNL1/TdCNL5 together show resistance, whereas Fielder with TdCNL5 alone was susceptible. Geographically, MLIW170/PM26 occurs in a few Southern populations of wild emmer wheat. Our study highlights an atypical NLR pair coordinately regulating powdery mildew resistance and provides a diversified resistance gene resource for wheat improvement. The powdery mildew resistance of the MLIW170/PM26 locus, which originated from wild emmer wheat, is determined by a genetically linked atypical NLR gene pair, TdCNL1 and TdCNL5, with TdCNL1 encoding an atypical nucleotide-binding leucine-rich repeat protein integrating a potassium-dependent sodium-calcium exchanger domain.