Hybridization of powdery mildew strains gives rise to pathogens on novel agricultural crop species

Summary

Beat Keller, Thomas Wicker and colleagues compare the genomes of 46 isolates of powdery mildew, Blumeria graminis. They find that B. graminis f. sp. triticale, a pathogen growing on triticale (a wheat × rye hybrid plant), is a hybrid of B. graminis f. sp. tritici and B. graminis f. sp. secalis, which grow on wheat and rye, respectively. Throughout the history of agriculture, many new crop species (polyploids or artificial hybrids) have been introduced to diversify products or to increase yield. However, little is known about how these new crops influence the evolution of new pathogens and diseases. Triticale is an artificial hybrid of wheat and rye, and it was resistant to the fungal pathogen powdery mildew (Blumeria graminis) until 2001 (refs. 1,2,3). We sequenced and compared the genomes