Dynamic Transcriptional Regulation of Water Deficiency-Responsive Genes by DNA Methylation in Barley (Hordeum vulgare L.)

One of the strategies determining rapid adaptation of plants to changing environmental conditions is the modification of DNA methylation level and methylation profile, what can result in modulation of gene expression. This study attempts to characterize the dynamics of drought stress-induced changes in DNA methylation in barley, as well as to identify early and late drought-responsive genes, which transcription may be affected by DNA methylation changes.

By using Methylation Sensitive Amplification Polymorphism Sequencing (MSAP-Seq), we identified numerous differentially methylated sites (DMS) affected by drought stress in barley leaves. Detailed profiling of the barley methylome at several time points during progressive water deficiency conditions, as well as rewatering phase, revealed its dynamic modulation under stress and recovery in terms of the quantity and localization of drought-induced changes. More than two thousands of drought-related DMSs were identified. Interestingly, changes occurring in the early drought phases were more persistent than those occurring in the late drought, which were highly reversible. Global-wide transcriptome profiling, using mRNA-Seq in each of the time points, allowed for a detailed characterization of expressional profiles of genes modulated under drought. Consequently, we identified early and late drought-responsive gene, which transcription could be potentially regulated by DNA methylation changes. Altogether our analyses suggest that the dynamic nature of methylome changes affecting the expression of water stress responsive genes, might be an important layer in regulatory machinery of stress response in large-genome crops.

The authors acknowledge financial support from the Polish National Science Centre (grant no. 2014/13/N/NZ2/01153).