Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı

Molecular Analysis on Barley (Hordeum vulgare L.) Under The Effect of Salt and Drought Stresses

In this study, the changes in antioxidant enzyme activities, synthesized transcription factors and physiological response of barley (Hordeum vulgare L. var. Tokak) under the effect of abiotic stress (salt stress and drought) were investigated.

In the barley embryo cultures, salt stress conditions were triggered by adding different concentrations of CaCl2 (10, 40, 50, 60 mM) in MS media. Control material was grown in standard MS medium. It was determined that salt stress in Tokak variety did not statistically affect the regeneration number but the increase in the salt concentration caused a decrease in the average stem length (p=0) in comparison to control material. While the average root length decreased in comparison to control material depending on the increase in salt concentration (p<0.01), root development was totally inhibited by treating 50 and 60 mM CaCl2.

Drought stress was provided by incubating the 10-day old plants, grown in control media, for 1, 3, 5 and 24 hours in 20 % PEG added MS media. Changes in activities of antioxidant enzymes (peroxidase, catalase and superoxide dismutase), playing role in abiotic stress response, were investigated in the plants in control media and under drought and salt stress effects. Compared to the control material on increase is observed in antioxidant enzyme activities of Tokak varieties, which is under both salt and drought stress. The highest activity observed in peroxidase enzyme was under 60 mM salt and 1 hour drought application. Where as in catalase enzyme the highest activity was under 10 mM salt and 3 hours drought application and in superoxide dismutase enzyme peak activities observed in 60 mM salt and 5 hours salt application. As a result of those, It is determined that abiotic stress tolerance was closely associated with the antioxidant defence system.

General transcription factors that regulate the synthesis of several proteins responsible for stress tolerance in Tokak variety were analysed by RT-PCR. It was determined that DREB2 and WRKY38 were the transcription factors responsible for both drought and salt stress tolerance. It was experimentally revealed that WRKY38 gene expression increased in response to salt stress.

Present salt and drought tolerances of economically valuable Tokak variety were determined in this research project. Antioxidant enzyme activities responsible for plant defence against stress and general transcription factors playing role in the synthesis of proteins that regulate the stress response were identified. The findings of this study will contribute to future investigations of mechanisms that are responsible for abiotic stress tolerance in barley; moreover, they form preliminary results for a future study on increasing the stress tolerance of Turkish barley varieties by gene manipulation.

KARTAL Gönül
Danışman : Prof.Dr.Nermin GÖZÜKIRMIZI

Anabilim Dalı : Moleküler Biyoloji Ve Genetik

Mezuniyet Yılı : 2008

Tez Savunma Jürisi : Prof.Dr. Nermin GÖZÜKIRMIZI 

: Prof.Dr. Güler TEMİZKAN

: Prof.Dr. Avni KURU

: Prof.Dr. Keriman GÜNAYDIN

: Prof.Dr. Ahmet ZEHİR