Investigation of tolerance mechanism to salt stress of endemic halophyte scorzonera hieraciifolia plant

To clarify the salt tolerance mechanism of endemic halophyte Scorzonera hieraciifolia, the seedlings grown in tissue culture medium were exposed to different salt concentrations (0, 150, 300, 450, 600 mM NaCl) and changes in some physiological, biochemical and molecular parameters were determined. It was detected that leaf succulence increased in accordance with the increased salt concentration and the plants remained alive despite chlorophyll loss in the 600 mM NaCl applied shoots. Shoot fresh weight, dry weight, chlorophyll and carotenoid contents significantly reduced in the 450 and 600 mM salt applied shoots. Reactive oxygen species, membrane damage, proline and total soluble sugar andNa+, Cl- andK+ contents increased under salt stress conditions. It was observed that catalase (CAT) activity decreased in the shoots exposed to 450-600 mM NaCl. While the activities of superoxide dismutase (SOD), guaiacol peroxidase (GPOD), glutathione reductase (GR) and ascorbate peroxidase increased in all salt applications. Ascorbate and glutathione contents also increased in the shoots exposed to 300, 450 and 600 mM salt. In addition, protein contents of SOD and glutathione peroxidase (GPX) increased in parallel with increasing salt. The most increases of CAT and GR protein contents were observed at 300 mM and 450 mM NaCl, respectively. In the light of the obtained data, it was concluded that leaf-succulent endemic halophyte Scorzonera hieraciifolia could increase the succulency by up taking the water effectively through the accumulation of osmolite and salt in the cell and it could stimulate the antioxidant system and thus it is an extreme halophyte tolerating high salt concentration (600 mM).