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Home Διερεύνηση του φυσιολογικού ρόλου της γλουταμικής αφυδρογόνασης (GDH) υπό συνθήκες καταπόνησης με χρήση ΓΤΦ καπνού (Nicotiana tabacum)

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Identifier

000351227

Title

Διερεύνηση του φυσιολογικού ρόλου της γλουταμικής αφυδρογόνασης (GDH) υπό συνθήκες καταπόνησης με χρήση ΓΤΦ καπνού (Nicotiana tabacum)

Alternative Title

Determination of the physiological role of glutamate dehydrogenase (GDH) under stress conditions with the use of transgenic tobacco plants (N. tabacum)

Author

Βελάνης, Χρήστος Ν

Thesis advisor

Ρουμπελάκη-Αγγελάκη, Κ.Α

Abstract

Glutamate dehydrogenase (GDH, E.C 1.4.1.4) catalyses in vitro the oxidative deamination of L-Glutamate as well as the reductive amination a-ketoglutarate. Plant biologists have been struggling for more than three decades to reach a consensus upon the in planta physiological role of the enzyme. GDH is an oligomeric protein and in it’s native comformation it consists of two different subuinits (designated α- and β-), which are encoded by at least two nuclear non allelic genes. The two subunits assemble in every possible combination giving rise to seven different hexameric isoforms. Unlike the GDHs of microorganisms, plants’s enzymes function primarily towards the catabolic direction. However, it is possible that during stressful situations (e.g salinity) GDH may contribute to the main ammonia assimilatory pathway (GS/GOGAT cycle). In this study we have used transgenic tobacco plants which either overexpress the GDHs (one at a time or both genes simultaneously) or suppress one of the two genes. After treating these plants with high concentrations of salinity the GDH;A mRNA was found to accumulate, the imunoreactive α- subunit polypeptide was de novo synthesized and the corresponding anodic isoenzymes were assembled. Metabolic profiling of ¹⁵N-fed plants carried out by GC-MS analysis indicated that under salinity GDH may contribute to the main ammonia assimilatory pathway. A detailed phenotypic analysis was also preformed but our results did not indicate significant differences among the various lines tested.

Language

Greek

Subject

Ammonia assimication

GC/MS

Metabolic analysis

Salinity

Transgenic plants

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ΓΤΦ

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