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

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 (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 antioxidant activities and differentially methylated regions (DMRs). Genes in drought-tolerant varieties XL are rapidly and significantly methylated when exposed to drought stimulus. These DMRs-related genes in XL are significantly enriched in defense response and response to stimuli via gene-ontology enrichment analysis. Then, we focused on 1003 transcription factors and identified 15 specific DMRs-related transcription factors exhibiting specific methylation changes under drought stimuli. Finally, we identified three DMRs-related TFs ( HvRR12, HvRR2, and HvCSP41B ), where Arabidopsis homologs involve in responses to drought conditions. Altogether, abiotic stresses could be rapidly respond and mediated by methylation of transcription factors in hulless barely.