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Title: Over-expression of a tomato N-acetyl-L-glutamate synthase gene (SlNAGS1) in Arabidopsis thaliana results in high ornithine levels and increased tolerance in salt and drought stresses
Authors: Kalamaki, Mary S. 
Alexandrou, Dimitris 
Lazari, Diamanto 
Merkouropoulos, Georgios 
Fotopoulos, Vasileios 
Aggelis, Alexandros 
Carrillo-López, Armando 
Rubio-Cabetas, Maria J. 
Kanellis, Angelos K. 
Pateraki, Irini 
Major Field of Science: Agricultural Sciences
Field Category: Agricultural Biotechnology
Keywords: Arabidopsis thaliana;Arginine biosynthesis;Citrulline;Drought tolerance;N-acetyl-L-glutamate synthase;Ornithine;Salt stress;Seed germination;Transgenic plants
Issue Date: Apr-2009
Source: Journal of Experimental Botany, 2009, vol. 60, no. 6, pp.1859-1871
Volume: 60
Issue: 6
Start page: 1859
End page: 1871
Journal: Journal of Experimental Botany 
Abstract: A single copy of the N-acetyl-L-glutamate synthase gene (SlNAGS1) has been isolated from tomato. The deduced amino acid sequence consists of 604 amino acids and shows a high level of similarity to the predicted Arabidopsis NAGS1 and NAGS2 proteins. Furthermore, the N-terminus ArgB domain and the C-terminus ArgA domain found in SlNAGS1 are similar to the structural arrangements that have been reported for other predicted NAGS proteins. SlNAGS1 was expressed at high levels in all aerial organs, and at basic levels in seeds, whereas it was not detected at all in roots. SlNAGS1 transcript accumulation was noticed transiently in tomato fruit at the red-fruit stage. In addition, an increase of SlNAGS1 transcripts was detected in mature green tomato fruit within the first hour of exposure to low oxygen concentrations. Transgenic Arabidopsis plants have been generated expressing the SlNAGS1 gene under the control of the cauliflower mosaic virus (CaMV) 35S promoter. Three homozygous transgenic lines expressing the transgene (lines 1-7, 3-8, and 6-5) were evaluated further. All three transgenic lines showed a significant accumulation of ornithine in the leaves with line 3-8 exhibiting the highest concentration. The same lines demonstrated higher germination ability compared to wild-type (WT) plants when subjected to 250 mM NaCl. Similarly, mature plants of all three transgenic lines displayed a higher tolerance to salt and drought stress compared to WT plants. Under most experimental conditions, transgenic line 3-8 performed best, while the responses obtained from lines 1-7 and 6-5 depended on the applied stimulus. To our knowledge, this is the first plant NAGS gene to be isolated, characterized, and genetically modified.
ISSN: 1460-2431
DOI: 10.1093/jxb/erp072
Rights: This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Type: Article
Affiliation : Aristotle University of Thessaloniki 
Institute of Agrobiotechnology 
Cyprus University of Technology 
Universitat de Barcelona 
University of Thessaly 
Universidad Autonoma de Sinaloa 
Centro de Investigacion y Tecnologia Agroalimentaria 
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