Genome wide association mapping ofPyrenophora teresf.maculataandPyrenophora teresf.teresresistance loci utilizing natural Turkish wild and landrace barley populations

Unimproved landraces and wild relatives of crops are sources of genetic diversity that were lost post domestication in modern breeding programs. To tap into this rich resource, genome wide association studies in large plant genomes have enabled the rapid genetic characterization of desired traits from natural landrace and wild populations. Wild barley (Hordeum spontaneum), the progenitor of domesticated barley (H. vulgare), is dispersed across Asia and North Africa, and has co-evolved with the ascomycetous fungal pathogensPyrenophora teresf.teresandP. teresf.maculata, the casual agents of the diseases net form of net blotch and spot form of net blotch, respectively. Thus, these wild and local adapted barley landraces from the region of origin of both the host and pathogen represent a diverse gene pool to identify new sources of resistance, due to millions of years of co-evolution. The barley -P. terespathosystem is governed by complex genetic interactions with dominant, recessive, and incomplete resistances and susceptibilities, with many isolate-specific interactions. Here we provide the first genome wide association study of wild and landrace barley from the Fertile Crescent for resistance to both forms ofP. teres. A total of 14 loci, four againstP. teresf.maculataand ten againstPyrenophora teresf.teres,were identified in both wild and landrace populations, showing that both are genetic reservoirs for novel sources of resistance. We also highlight the importance of using multiple algorithms to both identify and validate additional loci.