Oxidative stress responses induced by uranium exposure at low pH in leaves of Arabidopsis thaliana plants.
Anthropogenic activities have led to a widespread uranium (U) contamination in many countries. The toxic effects of U at the cellular level have mainly been investigated at a pH around 5.5, the optimal pH for hydroponically grown plants. However, since the speciation of U, and hence its toxicity, is strongly dependent on environmental factors such as the pH, it is important to investigate the effects of U at different environmentally relevant pH levels. Although U is poorly translocated from the roots to the shoots, resulting in a low U concentration in the leaves, it has been demonstrated that toxic effects in the leaves were already visible after 1 day exposure at pH 5.5, although only when exposed to relatively high U concentrations (100 μM). Therefore, the present study aimed to analyse the effects of different U concentrations (ranging from 0 to 100 μM) at pH 4.5 in leaves of Arabidopsis thaliana plants. Results indicate that U induces early senescence in A. thaliana leaves as was suggested by a decreased expression of CAT2 accompanied by an induction of CAT3 expression, a decreased CAT capacity and an increased lipid peroxidation. In addition, miRNA398b/c is involved in the regulation of the SOD response in the leaves. As such, an increased MIR398b/c expression was observed leading to a decreased transcript level of CSD1/2. Finally, the biosynthesis of ascorbate was induced after U exposure. This can point towards an important role for this metabolite in the scavenging of reactive oxygen species under U stress.
Belgian Nuclear Research Centre (SCK•CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium; Hasselt University, Centre for Environmental Sciences, Agoralaan Building D, 3590 Diepenbeek, Belgium. Electronic address: eline.saenen@sckcen.be.
Eline
E
Saenen
Belgian Nuclear Research Centre (SCK•CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium. Electronic address: nele.horemans@sckcen.be.
Nele
N
Horemans
Belgian Nuclear Research Centre (SCK•CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium. Electronic address: nathalie.vanhoudt@sckcen.be.
Nathalie
N
Vanhoudt
Belgian Nuclear Research Centre (SCK•CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium. Electronic address: hildegarde.vandenhove@sckcen.be.
Hildegarde
H
Vandenhove
Belgian Nuclear Research Centre (SCK•CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium; Hasselt University, Centre for Environmental Sciences, Agoralaan Building D, 3590 Diepenbeek, Belgium. Electronic address: geert.biermans@FANC.FGOV.BE.
Geert
G
Biermans
Belgian Nuclear Research Centre (SCK•CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium. Electronic address: mvhees@sckcen.be.
May
M
van Hees
Belgian Nuclear Research Centre (SCK•CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium. Electronic address: jwannijg@sckcen.be.
Jean
J
Wannijn
Hasselt University, Centre for Environmental Sciences, Agoralaan Building D, 3590 Diepenbeek, Belgium. Electronic address: jaco.vangronsveld@uhasselt.be.
Jaco
J
Vangronsveld
Hasselt University, Centre for Environmental Sciences, Agoralaan Building D, 3590 Diepenbeek, Belgium. Electronic address: ann.cuypers@uhasselt.be.
Ann
A
Cuypers
D000975:Antioxidants / Q000378:metabolism; D017360:Arabidopsis / Q000378:metabolism / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D006863:Hydrogen-Ion Concentration; D018384:Oxidative Stress / Q000528:radiation effects*; D018515:Plant Leaves / Q000378:metabolism / Q000528:radiation effects; D014501:Uranium / Q000633:toxicity*
D000975:Antioxidants; D014501:Uranium
Arabidopsis thaliana; Oxidative stress; Senescence; Uranium toxicity; pH