ISHS Acta Horticulturae 528: VII International Symposium on Grapevine Genetics and Breeding
NITROGEN METABOLISM AND RECYCLING GENES CLONED FROM VITIS VINIFERA L. |
| Authors: | N.I. Primikirios, F. Lefort, K.A. Roubelakis-Angelakis, K.A. Loulakakis |
| Keywords: | Arginine decarboxylase, glutamate dehydrogenase, glutamate synthase, glutamine synthetase, gene expression, nitrogen metabolism, grapevine (Vitis vinifera L.) |
| Abstract:
In an effort to elucidate the characteristics of ammonia assimilating enzymes and their possible interrelationship to polyamine biosynthesis, we have studied the molecular and expression characteristics of grapevine glutamine synthetase (GS), glutamate synthase (GOGAT), glutamate dehydrogenase (GDH) and arginine decarboxylase (ADC). A cDNA library from grapevine cell suspension was constructed and screened for the above enzymes. Three full cDNA clones encoding GS, two partial for Fd-GOGAT, one full length for GDH and one cDNA clone for ADC were isolated and characterized. The three GS clones were structurally distinct encoding for cytosolic isoforms of the grapevine enzyme. The Fd-GOGAT cDNAs encode for the carboxy- and near to amino-terminal sequences of the putative molecule. The deduced GDH amino acid sequence showed relatively higher homology to GDH from archaebacteria species, than to those from eucaryotes and eubacteria. Amino acid sequence comparison revealed that grapevine ADC exhibited 70–80% identity with other dicot and only 50% identity to monocot ADCs. The gene organization and the expression characteristics of the genes corresponding to the seven cDNAs were determined by DNA and RNA blots, respectively. The transcripts corresponding to these cDNAs showed differential accumulation in the various grapevine tissues tested. Culture of cell suspension in media containing modified nitrogen source resulted in differential expression of the GS, Fd-GOGAT and GDH genes, whereas ADC transcript levels remained constant. | |
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