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İstanbul Üniversitesi (2016)

Gene expression profiles under salt stress in barley

UÇARLI Cüneyt

Titre : Gene expression profiles under salt stress in barley

Tuz stresi etkisindeki arpa bitkilerinin gen anlatım profilleri

Auteur : UÇARLI Cüneyt

Université de soutenance : İstanbul Üniversitesi

Grade : Doktora Tezi 2016

Résumé partiel
Salinity is one of the most serious abiotic stress factors which restricts plant development and crop yield in arid and semi-arid regions. High salinity affects the plant via water stress, ion toxicity, disruption of membrane integrity, alteration metabolic process, reduction of cell expansion and division. All of these effects reduce plant growth and development and even may lead death. In this thesis study, salt stress was applied in laboratory conditions to some varieties cultivated in our country of naturally-salt tolerant barley (Hordeum vulgare L. cvs. Tokak157/37, Erginel90, Tarm92, and Martı) and response of the plants to the stress was examined with physiological and molecular techniques. Germination is the most sensitive developmental stage to the salt in barley. In the study, it was determined that during germination water absorption in barley seed decreased in 37%, and 160 mM salt concentration is a critical value which effects seed water uptake. In later stages, 80 mM salt treatment caused a significant reduction in shoot length, and 120-160 mM NaCl salt concentrations restricted root length of barley seedlings. Shoot growth in salinity was better in six-row varieties compared with two-row varieties. Osmolytes accumulation were significantly increased during germination stage of tissues after 80 mM of salt concentration. At vegetative stage, when barley plants kept in Hoagland solutions including 160 mM NaCl were examined in their response to salt stress, osmolyte accumulation was increased depending on salt stress and time (the highest level was 1072 mOsmol/kg). Membrane ion leakage is an indicator of cell membrane damage. In the study, 26 hours after 160 mM NaCl treatment (in Martı variety), membrane damage in root tissues caused by salt was 90% level. Salt stress also caused a significant damage in cell membranes of the shoot tissues (e.g. in Tokak157/37 variety control : 9% ; stress : 37% ). On the other hand, application of 0.5 mM linoleic acid in hydroponic system was effective in decreasing membrane damage and increasing osmolyte accumulation. In the thesis study, expressions of plant stress responsive genes in different pathways and two transcription factors were analyzed with RT-PCR and real-time PCR (qRT-PCR). Four genes were selected as HvGST6, HvCu/znSOD, HvAPX, HvCAT2. antioxidant related genes and expressions of the HvGST6, HvCu/znSOD were constitutive in both roots and shoots. While HvAPX expression was induced by salinity stess, HvCAT2 had a lower expression, even in high amounts of salt. Expressions of HvDRF2 and HvWRKY12 transcription factors were quite low in root and shoots, however, stress leads to significantly higher transcript accumulation

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