The Study of SOS Genes Expression in Mutant Barley Root under Salt Stress

Soil salinity is one of the most critical factors reducing crop yield. SOS signaling is one of the significant pathways that regulate ion homeostasis and it has the important role in mechanism of plant resistance to environmental stresses such as salt stress. Roots are the first organ of plants exposed to salt, so the role of genes involved in this pathway and their relation to salt tolerance were investigated between 73-M4-30, a salt tolerant mutant genotype, and Zarjou, as its wild type, genotypes. In this research, patterns of expression of HvSOS1, HvSOS2 (CIPK24) and HvSOS3 (CBL4) genes were studied under 300 mM salt concentration at 0 (control), 3, 6, 12, 24, 48, 72 and 96 hours between two genotypes. Quantitative RT-PCR analysis showed that the expression levels of these three genes under salt stress in root tissue of the salt-tolerant mutant genotype in compared to its wild genotype were much more and stronger in early time of 6-hour. The parallel up-regulation of these three genes in the root tissue of the mutant genotype demonstrated the activity of Na+/H+ antiporter and Na+ exclusion toward apoplast as well as its transportation from the root to the shoot. The lack of similarity in expression pattern of SOS genes between the two genotypes of salt-tolerant mutant and wild parent showed that the mutation could alter the ability of the salt tolerant mutant genotype in the use of ionic homeostasis in response to the salt stress.