Transcriptomics of mild drought response in barley

The data present global gene expression profiling of roots of two barley genotypes with contrasting ability to cope with drought stress. We used the whole root system and the second leaf of CamB and Maresi genotypes subjected to 10-days of mild drought at seedling stage. The transcriptomes of leaves served in the presented study as a background to depict, which genes may respond with the expression changes in an organ-specific manner. Our data indicate that the mild drought resulted in more changes in the transcriptomes of roots than in the leaves and more differentially expressed genes (DEGs) were root-specific. We also found that similar number of DEGs were induced or repressed by the stress in roots of CamB genotype, whereas in roots of more drought susceptible Maresi a down-regulation of gene expression prevailed. We identified 88 genes encoding transcription factors and gene expression regulators that were differentially expressed in roots and the majority of them were root-specific. We discuss their probable function in drought response and tolerance and predicted a possible regulatory network downstream of selected transcription factors. Two barley genotypes were used for the study: a German semidwarf cultivar Maresi and a Syrian breeding line Cam/B1/CI08887//CI05761 (CamB), adapted to dry environments. Two water regimes were used: control conditions and a mild drought, which was applied at the 3-leaf seedling stage and lasted for 10 days. The experiment was carried out in three replicates and tissue for RNA extraction was collected from five plants per replicate.