Differential physiological and molecular responses of three-leaf stage barley (Hordeum vulgare L.) under salt stress within hours

Salt stress is first perceived by the plant roots and inhibits plant growth in the short-term by inducing osmotic stress caused by decreased water availability. In this study, 160 mM NaCl was applied to three-leaf-stage barley plants (Hordeum vulgare L. cv. Marti) for a short period (0, 2, and 26 h) Osmolyte accumulation and ion leakage was significantly increased after salt stress treatment compared with control conditons in both leaf and root tissues within 2 h. We have also found that expressions of transcription factors HvDRF2 and HvWRKY12, associated with abiotic stress including salinity and drought stress, were quite low in root and shoots in control conditions; however, salt stress resulted into upregulation of HvDRF2 expression as 28.8- and 26.6-fold in roots and leaves, respectively, within 26 h. While salt stress-induced significantly upregulation of HvPR1A (26.4-fold) HvNHX1 (sevenfold) in 2 h at P < 0.05 level, significant upregulation of HvMT2 (8.2-fold) and HvDHN3 (4.7-fold) was observed at 26 h after salt treatment in roots. In leaves, HvMT2 (12.7-fold), HvNHX1 (12.1-fold) and HvBAS1 (3.4-fold) were significantly upregulated under salt stress. Only HvLHCB mRNA level was significantly decreased as 2- and 5.6-fold in leaf tissues with salinityin 2 and 26 h, respectively.