Dissection of the molecular mechanism of salinity stress tolerance in halophyte plant, Aeluropus littoralis using AlSOS genes

Salinity stress is one of the most important environmental stresses that affects crop production. Salt Overly Sensitive regulation path is an important route in the regulation of ion homeostasis. In this study, the expression patterns of AlSOS1, AlSOS2 and AlSOS3 genes were evaluated in the salt tolerant plant, Aeluropus littoralis under 0, 200, 400 and 600 mM sodium chloride and after 0, 8, 16, 24, 48 and 72 h of the stress exposure. Salinity stress significantly increased the expression of all genes compared to the control. In 200 mM NaCl treatment, AlSOS1 and AlSOS2 expression increased in various time courses and peaked at 72 h after the stress exposure. In 400 and 600 mM NaCl treatment, however, the maximum expression of AlSOS1 was observed at 48 h after the stress. AlSOS2 was highly expressed at the salt concentrations of 400 and 600 mM after 48 h and 24 h, respectively. The maximum rate of AlSOS3 transcription was recorded in 400 and 600 mM NaCl after 24 h and 16 h, respectively. Different mechanism of the effect of AlSOS3 on AlSOS2, effect of AlSOS2- AlSOS3 complex on AlSOS1 and differences in the act of the genes are of the reasons for the variations in the gene expression. These results suggest that in severe stress conditions, the reaction of genes would be rapid and with different patterns. AlSOS3 showed a different pattern of the expression comparing to the two other genes which implies differences in the gene regulation mechanism.