Date

2007

Author

Kayıhan, Ceyhun

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In this study, effect of cold stress and recovery on the superoxide dismutase (SOD) activities and the expression levels of Cu/ZnSOD gene were investigated in two barley cultivars (Tarm-92-winter type, Zafer-160-spring type). Eight days old barley seedlings were subjected to two different cold stresses; chilling stress at 4°C for 1, 3, 7 days and freezing stress at -3°C and -7°C. Analyses were performed both on leaf and root tissues. The SOD activities and isozyme patterns were determined by Native PAGE activity staining technique. Relative RT-PCR was used for the transcript levels of Cu/ZnSOD gene. The SOD activities and expression levels of control and cold stressed plants were compared by densitometric analysis. Under chilling stress, the activities of Cu/ZnSODx and Cu/ZnSOD2 did not have any significant change in leaf and root tissues of both cultivars. However, the expression levels of Cu/ZnSOD gene were more variable than activity results. After -3°C freezing stress, the activities of SOD enzyme in leaf tissues of Tarm-92 increased significantly, however, these activities significantly decreased in leaves of Zafer-160. These results suggested that both cultivars were not affected by chilling stress in terms of SOD enzyme activities and expression levels. Furthermore, under freezing stress conditions, the increment of SOD activities and expression levels in Zafer-160 was higher than Tarm-92. In conclusion, the changes in SOD isozyme activities and expression levels may not be enough for understanding of the cold stress mechanism. Therefore, further studies have to be carried on other antioxidant enzyme systems.

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http://etd.lib.metu.edu.tr/upload/3/12608513/index.pdf
https://hdl.handle.net/11511/16896

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Graduate School of Natural and Applied Sciences, Thesis