LAUSR

H3K9ac, an epigenetic marker, is widely distributed in plant genomes. H3K9ac enhances gene expression, which is highly conserved in eukaryotes. However, genome-wide study of H3K9ac in monocot species is limited, and the changes in H3K9ac under drought stress for individual genes are still not clear. We analyzed changes in the H3K9ac level of Brachypodium distachyon under 20% PEG-6000-simulated drought stress conditions. Furthermore, we performed chromatin immunoprecipitation followed by next generation sequencing (ChIP-seq) on H3K9ac to reveal the changes in H3K9ac for individual genes at the genome-wide level. Our study showed that H3K9ac was mainly enriched in gene exon regions. Drought increased or decreased the H3K9ac level at specific genomic loci. We identified 40 genes associated with increased H3K9ac levels and 36 genes associated with decreased H3K9ac levels under drought stress. Further, RT-qPCR analyses showed that H3K9ac was positively associated with gene expression of those drought-responsive genes. We conclude that H3K9ac enhances the expression level of a large number of drought-responsive genes under drought stress in B. distachyon. The data presented here will help in revealing the correlation of some specific drought-responsive genes and their enriched H3K9ac levels in the model plant B. distachyon.