ABSTRACT

Wild-type Arabidopsis thaliana Col-0 and a knockout T-DNA mutant for the ASN2 gene encoding Asparagine synthetase (AS, EC 6.3.5.4) (asn2-1) was used, to investigate the primary effects of ammonium under salt stress. Plants were grown for one month in hydroponic culture and then exposed to either 2 mM NH4 or 2 mM NH4+ and 100 mM NaCl, for 6 hours. In the wild-type, the ammonium-salt co-treatment increased the activities of both glutamine synthetase (GS, EC 6.3.1.2) and the aminating glutamate dehydrogenase (GDH) (NADHGDH, EC 1.4.1.2), thus can be linked to ammonium accumulation. A slight increase in GS and GDH activities were noted in the asn2-1 lines, despite there being more endogenous ammonium accumulation. These results suggest that in asn2-1 lines, GS and the aminating GDH activity increase may be mediated by other metabolites when the ASN2 gene is lacking. The co-treatment elevated too, the expression of the genes GLN1.1 and GLN1.2 encoding for GS1 in both lines. The results suggest that the co-treatment led to the upregulation of ammonium assimilating enzymes, GS and GDH. The slight enzyme activity increase in the mutant lines may suggest a potential role for Asparaginein response to salt stress. Keywords: Ammonium assimilation, Arabidopsis thaliana, asparagine synthetase enzyme, glutamine synthetase, salt stress
Publication date: 01/06/2020

https://ijbpas.com/pdf/2020/June/MS_IJBPAS_2020_5037.pdf

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https://doi.org/10.31032/IJBPAS/2020/9.6.5037