Antioxidant status in herbaceous plants growing under elevated CO2 in mini-FACE rings

Here we present studies on the antioxidant status of a semi-natural grassland community, permanently growing in mini-FACE rings under elevated concentrations of atmospheric CO2 (560 μmol mol−1). In general, in leaves of Dactylis glomerata L. and Trifolium repens L., no differences between ambient and elevated CO2 were detected as concerns protein content, activity of oxidant-scavenging enzymes (catalase, superoxide dismutase, ascorbate peroxidase and guaiacol peroxidase), and lipid peroxidation. The activity of antioxidant-regenerating enzymes (monodehydroascorbate reductase, dehydroascorbate reductase and glutathione disulfide reductase) and the content of antioxidants (ascorbic acid, dehydroascorbic acid, reduced glutathione and glutathione disulfide) showed remarkable variability between leaves from plants grown in ambient and CO2-enriched mini-FACE rings. Thus, in general it can be concluded that the effects of elevated CO2 at environmentally relevant concentrations on the leaf antioxidant status of a grassland community are extremely variable, species-specific and rather limited.