Induction of Oxidative Stress and Antioxidative Mechanisms in Arabidopsis thaliana after Uranium Exposure at pH 7.5

• Published in: International journal of molecular sciences Vol. 16; no. 6; pp. 12405 - 12423
• Main Authors: Saenen, Eline, Horemans, Nele, Vanhoudt, Nathalie, Vandenhove, Hildegarde, Biermans, Geert, Van Hees, May, Wannijn, Jean, Vangronsveld, Jaco, Cuypers, Ann
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 02.06.2015; MDPI
• Subjects: Antioxidants - metabolism; Arabidopsis - drug effects; Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; ascorbate-glutathione cycle; Ascorbic Acid - metabolism; Dose-Response Relationship, Drug; Flowers & plants; Gene expression; Gene Expression Regulation, Plant - drug effects; Glutathione - metabolism; Hydrogen-Ion Concentration; Oxidative Stress; Plant Leaves - drug effects; Plant Leaves - metabolism; Plant Roots - drug effects; Plant Roots - metabolism; Uranium; Uranium - pharmacology; uranium toxicity; Arabidopsis thaliana; uranium toxicity; ascorbate-glutathione cycle; gene expression; oxidative stress
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms160612405

To evaluate the environmental impact of uranium (U) contamination, it is important to investigate the effects of U at ecologically relevant conditions. Since U speciation, and hence its toxicity, strongly depends on environmental pH, the present study aimed to investigate dose-dependent effects of U at pH 7.5. Arabidopsis thaliana plants (Mouse-ear Cress) were exposed for three days to different U concentrations at pH 7.5. In the roots, the increased capacities of ascorbate peroxidase and glutathione reductase indicate an important role for the ascorbate-glutathione cycle during U-induced stress. However, a significant decrease in the ascorbate redox state was observed after exposure to 75 and 100 µM U, indicating that those roots are severely stressed. In accordance with the roots, the ascorbate-glutathione cycle plays an important role in the antioxidative defence systems in A. thaliana leaves exposed to U at pH 7.5 as the ascorbate and glutathione biosynthesis were upregulated. In addition, small inductions of enzymes of the antioxidative defence system were observed at lower U concentrations to counteract the U-induced stress. However, at higher U concentrations it seems that the antioxidative defence system of the leaves collapses as reductions in enzyme activities and gene expression levels were observed.