Molecular Mechanism of Salinity Stress Tolerance in Barley (Hordeum vulgare L.) via Meta-Analysis of Transcriptome Data

Salt stress, as the most important abiotic stress, limits growth of plants and causes extensive damage to agricultural production worldwide. Therefore, it is necessary to identify genes that play a key role in tolerance to salt stress in plants through the analysis of transcriptome data such as microarray and High-Throughput Sequencing (HTS or NGS). In the present research, the combined analysis of microarray data by R packages for Hordeum vulgare L. under salinity stress identified 685 upregulated meta-DEGs (differentially expressed genes) and 766 downregulated meta-DEGs. The upregulated genes mostly belong to abiotic stress tolerance and hormone biosynthesis, and the downregulated genes pertain to late embryogenesis abundant protein and salinity stress response. GO terms in the upregulated genes are mostly associated with response to external and internal stresses; and in the downregulated genes, they are mostly associated with cellular metabolism. In the up and down meta-DEGs by KEGG, most of the genes connected to salinity stress included PP2C, ABF, AGT, and ChiB and F-box connected to the downregulated genes. Moreover, Transcription Factors (TFs) in the up and downregulated meta-DEGs with high frequency included AP2, ERF, bZIP, and bHLH. Most of the hub upregulated genes acquired from this research were metabolite biosynthesis and photosynthesis-related; and the hub downregulated genes were mainly the tricarboxylic acid cycle and glycolysis processes-related. Finally, a comparison was made between this meta-analysis and data obtained from other investigations. The findings validated their up and down expression. Our results give a new understanding about the molecular mechanism and present many TFs and candidate genes for salt stress tolerance in barley breeding programs.