Allele Mining Using the Barley Nested Association Mapping Population HEB-25

Extending biodiversity is a key issue to cope with the current challenges in agriculture where biotic and abiotic stresses threaten future productivity. In this regard, we recently developed the barley nested association mapping (NAM) population HEB-25 (Halle exotic barley). HEB-25 consists of 1,420 BC1S3 lines, sub-divided into 25 families, which originate from crosses of the elite spring barley cultivar Barke with 25 wild barley donors (Hordeum spontaneum and H. agriocriton). HEB-25 is well suited in three ways. (1) to study biodiversity of barley wild relatives, (2) to identify, map and, ultimately, clone genes controlling agronomic traits and (3) to transfer favorable exotic alleles into the elite barley gene pool.

To accomplish this, life history traits and multiple pathogen resistances at seedling and adult plant stages have been studied in HEB-25 during the seasons 2011-2013. In addition, HEB-25 was genetically characterized with the 9k barley iSELECT chip. Subsequently, genome-wide association studies (GWAS), applying mixed linear models and multiple regression approaches, were carried out. In this way, exotic QTL alleles were identified, which control the studied traits.

During the talk, we report on mapping donor-specific QTL alleles controlling leaf rust resistance and threshability. For both traits, QTL effects could be measured across multiple donor families or restricted to individual HEB families. Our findings indicate the presence of common and individual donor allele effects in HEB-25, respectively. Our studies demonstrate that HEB-25 is a rich reservoir to identify exotic donor alleles, which may be used in barley genomics and barley breeding.