The quest for novel powdery mildew and yellow rust resistance genes among Einkorn Wheat germplasm

Powdery mildew (Pm) and yellow rust (Yr) fungal diseases, caused by the obligate parasites Blumeria graminis f.sp. tritici (Bgt) and Puccinia striiformis f.sp. tritici (Pst), respectively, are devastating crop diseases. The ancient Einkorn diploid wheat, Triticum monococcum, is a valuable potential source for novel resistance genes. We have screened a collection of 128 T. monococcum accessions from 20 different countries and classified them into three groups: (i) 107 lines resistant to powdery mildew isolate Bgt#70; (ii) 17 lines resistant to stripe rust isolate Pst#5006; and (iii) 15 lines highly resistant to both powdery mildew and yellow rust. The lines that are resistant to both pathogens were crossed with susceptible lines to generate genetic mapping populations. We also extracted DNA from all 128 accessions and checked if they harbor known powdery mildew R genes. We identified four accessions that harbor PmG16 (derived from Wild emmer wheat), and four other accessions that harbor Pm60 (derived from T. urartu). Further work is underway to genetically map the R-genes to chromosomes. In addition, we plan to characterize the histopathology of the host-pathogen interaction and develop a genetic transformation and regeneration system for T. monococcum that will be used as a diploid model for studying Triticeae biology and genomics. In summary, cultivated wheat is continually exposed to various pathogens causing significant yield losses. The introgression of novel resistance genes from wheat relatives into cultivated bread wheat can enrich the genetic resources available for disease resistance breeding.