Student:	Cansu ALTUNTAŞ
Supervisor:	Prof. Dr. Rabiye TERZİ
Department:	Biyoloji
Institution:	Graduate School of Natural and Applied Sciences
University:	Karadeniz Technical University Turkey

Title of the Thesis:	INVESTIGATION OF TOLERANCE MECHANISM TO SALT STRESS OF ENDEMIC HALOPHYTE SCORZONERA HIERACIIFOLIA PLANT
Level:	Ph.D.
Acceptance Date:	16/1/2020
Number of Pages:	87
Registration Number:	Di1353

Summary:

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).

Keywords: Scorzonera hieraciifolia, Salt stress, Halophyte, Succulent, Antioxidant system