Cytosolic Glutamine Synthetase Gln1;2 Is the Main Isozyme Contributing to GS1 Activity and Can Be Up-Regulated to Relieve Ammonium Toxicity
| Autor: | Thomas C. de Bang, Miao Guan, Carsten Pedersen, Jan K. Schjoerring |
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| Rok vydání: | 2016 |
| Předmět: |
0106 biological sciences
0301 basic medicine chemistry.chemical_classification biology Physiology Mutant Wild type Plant Science biology.organism_classification 01 natural sciences 03 medical and health sciences chemistry.chemical_compound 030104 developmental biology Biochemistry chemistry Glutamine synthetase Arabidopsis Shoot Genetics Arabidopsis thaliana Ammonium Amino acid synthesis 010606 plant biology & botany |
| Zdroj: | Plant Physiology. 171:1921-1933 |
| ISSN: | 1532-2548 0032-0889 |
| Popis: | Cytosolic GS1 (Gln synthetase) is central for ammonium assimilation in plants. High ammonium treatment enhanced the expression of the GS1 isogene Gln-1;2 encoding a low-affinity high-capacity GS1 protein in Arabidopsis (Arabidopsis thaliana) shoots. Under the same conditions, the expression of the high-affinity low-capacity isoform Gln-1;1 was reduced. The expression of Gln-1;3 did not respond to ammonium treatment while Gln-1;4 and Gln-1;5 isogenes in all cases were expressed at a very low level. Gln-2 was highly expressed in shoots but only at a very low level in roots. To investigate the specific functions of the two isogenes Gln-1;1 and Gln-1;2 in shoots for ammonium detoxification, single and double knock-out mutants were grown under standard N supply or with high ammonium provision. Phenotypes of the single mutant gln1;1 were similar to the wild type, while growth of the gln1;2 single mutant and the gln1;1:gln1;2 double mutant was significantly impaired irrespective of N regime. GS1 activity was significantly reduced in both gln1;2 and gln1;1:gln1;2. Along with this, the ammonium content increased while that of Gln decreased, showing that Gln-1;2 was essential for ammonium assimilation and amino acid synthesis. We conclude that Gln-1;2 is the main isozyme contributing to shoot GS1 activity in vegetative growth stages and can be up-regulated to relieve ammonium toxicity. This reveals, to our knowledge, a novel shoot function of Gln-1;2 in Arabidopsis shoots. |
| Databáze: | OpenAIRE |
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