Intensified Selection, Elevated Mutations, and Reduced Adaptation Potential in Wild Barley in Response to 28 Years of Global Warming

Many studies have investigated the threat of climate change on wild plants, but few have investigated the genetic responses of crop wild relative populations under threat. We characterized the genetic responses of 10 wild barley (Hordeum spontaneum K. Koch) populations in Israel, sampling them in 1980 and again in 2008, through exome capture and RNA-Seq analyses. Sequencing 48 wild barley samples of these populations representing two collection years generated six million SNPs, and SNP annotations identified 12,926 and 13,361 deleterious SNPs for 1980 and 2008 samples, respectively. The assayed wild barley samples displayed intensified selective sweeps and elevated deleterious mutations across seven chromosomes in response to 28 years of global warming. On average, the 2008 samples had lower individual and population mutational burdens, but the population adaptation potential was estimated to be lower in samples from 2008 than in 1980. These findings highlight the genetic risks of losing wild barley under global warming and support the need to conserve crop wild relatives.