Genome-Wide DNA Methylation Dynamics During Drought Responsiveness in Tibetan Hulless Barley

Abstract Differences in drought stress tolerance within diverse grass genotypes have been attributed to epigenetic modifications. DNA methylation is an important epigenetic alteration regulating responses to drought-stress. However, its effects on drought-tolerance are poorly understood in Tibetan hulless barley. Here, bisulfite sequencing was conducted to profile the DNA methylation patterns of drought-tolerant variety XL and drought-sensitive one DQ under drought and control conditions. A total of 5843 million reads were generated. We found the significant genome-wide changes in CHH methylation rates between XL and DQ, while CG or CHG methylation rates did not. Besides that, the two contrasting varieties do reveal distinct responses to drought-stress in differentially methylated region (DMR) numbers and antioxidant activities. Genes in drought-tolerant varieties XL are rapidly and significantly methylated to alleviate the drought stress. DMR related genes in XL might involve in defense response and response to stimuli, which are confirmed by gene ontology analysis. Then, we focused on 1003 transcription factors and identified 15 specific DMR related transcription factors exhibiting specific methylation changes under drought stimuli. Finally, we identified three DMR related TFs (HVUL6H08680.2, HVUL4 h39100.2, and HVUL2H41931.2) where Arabidopsis homologues involve in responses to drought conditions. Altogether, DNA methylation regulate responsiveness to environmental stimuli, which could be mediated by methylation of transcription factors in hulless barely.