Toward Fine Mapping of a Powdery Mildew Resistance Gene in a Hordeum vulgare/ bulbosum Introgression Line

Powdery mildew (PM) caused by Blumeria graminis f.sp. hordei (Bgh) is one of the main foliar diseases on barley (Hordeum vulgare L.) leading to severe economic losses worldwide. For disease resistance, wild barley relatives have been considered as valuable genetic diversity resources in barley breeding. However, most sources of PM resistance have been overcome by the emergence of new virulent races within the pathogen. Therefore, new durable and broadly acting sources of resistance are necessary for a long-term success of disease resistance in barley. The secondary gene pool of barley (Hordeum bulbosum L.) is a potential source of resistance genes for barley improvement. Despite crossing barriers, hybridization and recombination between two Hordeum genomes allow the introgression of H. bulbosum chromosome segments into barley carrying novel resistance genes. The aim of the project is to positionally clone a H. bulbosum-derived resistance gene introgressed to cultivated barley. Novel Single Nucleotide Polymorphism (SNP) markers will be developed by genotyping-by-sequencing for two Hordeum vulgare/bulbosum introgressions lines conferring resistance to Bgh. Resistant recombinants with small introgression size and a high marker density will be used for map-based cloning of genes underlying Bgh resistance. Based on the physical/genetic map, gene-flanking markers will be employed to identify a barley BAC contig corresponding to the orthologous region of the H. bulbosum genome.