Redox regulation of free amino acid levels in Arabidopsis thaliana.
Abiotic stresses induce oxidative stress, which modifies the level of several metabolites including amino acids. The redox control of free amino acid profile was monitored in wild-type and ascorbate or glutathione deficient mutant Arabidopsis thaliana plants before and after hydroponic treatment with various redox agents. Both mutations and treatments modified the size and redox state of the ascorbate (AsA) and/or glutathione (GSH) pools. The total free amino acid content was increased by AsA, GSH and H2O2in all three genotypes and a very large (threefold) increase was observed in the GSH-deficient pad2-1 mutant after GSH treatment compared with the untreated wild-type plants. Addition of GSH reduced the ratio of amino acids belonging to the glutamate family on a large scale and increased the relative amount of non-proteinogenic amino acids. The latter change was because of the large increase in the content of alpha-aminoadipate, an inhibitor of glutamatic acid (Glu) transport. Most of the treatments increased the proline (Pro) content, which effect was due to the activation of genes involved in Pro synthesis. Although all studied redox compounds influenced the amount of free amino acids and a mostly positive, very close (r > 0.9) correlation exists between these parameters, a special regulatory role of GSH could be presumed due to its more powerful effect. This may originate from the thiol/disulphide conversion or (de)glutathionylation of enzymes participating in the amino acid metabolism.
Agricultural Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Martonvásár, H-2462, Hungary.
Zsolt
Z
Gulyás
Department of Food Chemistry and Nutrition, Szent István University, Budapest, H-1118, Hungary.
Livia
L
Simon-Sarkadi
Agricultural Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Martonvásár, H-2462, Hungary.
Eszter
E
Badics
Agricultural Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Martonvásár, H-2462, Hungary.
Aliz
A
Novák
Department of Food Chemistry and Nutrition, Szent István University, Budapest, H-1118, Hungary.
Zsuzsanna
Z
Mednyánszky
Agricultural Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Martonvásár, H-2462, Hungary.
Gabriella
G
Szalai
Agricultural Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Martonvásár, H-2462, Hungary.|Festetics Doctoral School, Georgikon Faculty, University of Pannonia, Keszthely, H-8360, Hungary.
Gábor
G
Galiba
Agricultural Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Martonvásár, H-2462, Hungary.
Gábor
G
Kocsy
D000596:Amino Acids / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001205:Ascorbic Acid / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005978:Glutathione / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D009154:Mutation; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D013312:Stress, Physiological
D000596:Amino Acids; D029681:Arabidopsis Proteins; D006861:Hydrogen Peroxide; D005978:Glutathione; D001205:Ascorbic Acid