Call of the Wild: Exploiting Hordeum vulgare spp. spontaneum for Barley Improvement

Barley (Hordeum vulgare spp. vulgare) is a widely cultivated cereal crop that is used for malting, feed, and food. It is vulnerable to a number of diseases and also changes in climate, especially temperature. To reduce the vulnerability of barley to various biotic and abiotic stresses and make future gains in yield, quality and adaptation, the genetic diversity present in wild species must be exploited. Toward this goal, three hundred and eighteen accessions of wild barley (Hordeum vulgare spp. spontaneum) were assembled in a panel called the Wild Barley Diversity Collection (WBDC). Accessions for the WBDC were selected based on various ecogeographic characters (e.g. longitude/latitude, elevation, high/low temperature, rainfall, etc.) and were from 19 different countries, mostly in the Fertile Crescent (77.4%), but also Central Asia (15.7%), North Africa (3.8%), and the Caucasus region (2.8%). The WBDC has been systematically evaluated for over 50 different traits. These include disease and insect resistance, agronomic traits, abiotic stress tolerance, nutritional components and morphological characters. A wide range of diversity was observed for nearly every trait examined highlighting the importance of wild barley as a source of new alleles. Additionally, over 10,000 molecular markers have been generated for the WBDC for preliminary genome-wide association mapping studies (GWAS) of traits, but many more are being added through a genotype-by-sequencing approach given the low linkage disequilibrium present in this subspecies. Many introgression line populations have been developed with WBDC accessions and may be useful sources of genetic diversity for barley breeding programs across the world.