A CNL protein in wild emmer wheat confers powdery mildew resistance.

Powdery mildew, a fungal disease caused byBlumeria graminisf. sp.tritici(Bgt), has a serious impact on wheat production. Loss of resistance in cultivars prompts a continuing search for new sources of resistance. Wild emmer wheat (Triticum turgidumssp.dicoccoides, WEW), the progenitor of both modern tetraploid and hexaploid wheats, harbors many powdery mildew resistance genes. We report here the positional cloning and functional characterization ofPm41, a powdery mildew resistance gene derived from WEW, which encodes a coiled-coil, nucleotide-binding site and leucine-rich repeat protein (CNL). Mutagenesis and stable genetic transformation confirmed the function ofPm41againstBgtinfection in wheat. We demonstrated thatPm41was present at a very low frequency (1.81%) only in southern WEW populations. It was absent in other WEW populations, domesticated emmer, durum, and common wheat, suggesting that the ancestralPm41was restricted to its place of origin and was not incorporated into domesticated wheat. Our findings emphasize the importance of conservation and exploitation of the primary WEW gene pool, as a valuable resource for discovery of resistance genes for improvement of modern wheat cultivars.