Identification and promoter analysis of the key drought tolerance involved genes in reproductive stage in barley using microarray data analysis.

Drought is the most important environmental stress that reduces crop yield. Therefore, research toward developing tolerant varieties is of great importance. In this study, microarray data analysis was used for identification of drought stress responsive genes and relevant hub genes in the reproductive stage of barley, and then their promoter analysis was performed. To achieve the goal, all the differentially expressed genes (DEGs) at drought conditions with fold changes ≥+2.5 and ≤-2.5 were identified between two microarray data-series in barley using FlexArray software. Bioinformatics analysis indicated that 559 genes were drought responsive at reproductive stage. The hub genes were distinguished using three Cyto-Hubba computational algorithms by Cytoscape software. Based on the hub analysis results, 10 unique (non-redundant) genes were identified as the most effective genes in response to drought stress. According to the gene ontology analysis of DEGs and hub genes, regulation of transcription were among the major groups indicating the importance of transcription factors (TFs) at drought tolerance mechanism. Amongst the hubs, several TFs such as HvCBF6, HvDRF1.3, LFL1, VP1, ABI5 and WRKY71 genes (belonged to AP2, WRKY and bZIP families) were observed. Promoter analysis was also revealed that some TF families including AP2, AT-hook family, bHLH, NAC, bZIP and MYB had binding site in 85% of promoters of the drought responsive genes and the hub genes in barley. Studying these transcription factors can help in better identification of drought tolerance mechanism in barley.