Biochemical Parameters as Biomarkers for the Early Recognition of Environmental Pollution on Scots Pine Trees. II. The Antioxidative Metabolites Ascorbic Acid, Glutathione, a-Tocopherol and the Enzymes Superoxide Dismutase and Glutathione Reductase

Department of Soil Sciences, UFZ Centre for Environmental Research Leipzig-Halle, Theodor-Lieser-Str. 4-9, D-06120 Halle, Germany. Fax: +49 (345) 5585449. E-mail: [email protected] * Author for correspondence and reprint requests Z. Naturforsch. 56c, 767-780 (2001); received April 20/May 23, 2001 Pinus sylvestris L., Sulfur Dioxide, Antioxidants Field investigations with Scots pine trees (Pinus sylvestris L.) were performed in eastern Germany, where ambient S 0 2, NOx and 0 3 concentrations differed significantly in 1992-99 at three sites, namely Neuglobsow (yearly mean S 0 2 in 1992: 9 [xg m-3), Taura (yearly mean S 0 2 in 1992: 54 (ig m 3) and Rösa (yearly mean S 0 2 in 1992: 73 ng m-3). To investigate the effects of S 02, NOx and 0 3 on antioxidants (superoxide dismutase, ascorbic acid, glutathione, glutathione reductase, a-tocopherol) and pigments including chlorophyll fluorescence as well as visible damage symptoms in the form of needle yellowing and tip necroses, needles of the 1st and 2nd age class from young and mature trees were collected at the sites every October. Eight years after the start of the field study in 1992, the ambient S 0 2 concentrations had decreased significantly at Neuglobsow (yearly mean S 0 2 in 1999: 4 p,g m-3), Taura (yearly mean S 0 2 in 1999: 5 [xg m~3) and Rösa (yearly mean S 0 2 in 1999: 5 ng m~3). NOx and 0 3 differed less at the three sites and showed no temporal variations. Whole needle glutathione continuously decreased, although concentrations were higher in needles of the 1 st and 2 nd age class from the polluted sites Taura and Rösa than the unpolluted site Neuglobsow. The activities of glutathione reductase exhibited the same site-related differences and temporal variations and were correlated with concentrations of oxidized glutathione (GSSG). In con­ trast, the activities of the enzyme superoxide dismutase and the concentrations of whole needle ascorbic acid remained unchanged over the period. Only at the end of the investiga­ tion period did the concentrations of oxidized ascorbic acid (dehydroascorbate) increase in six-month-old needles at the polluted sites Taura and Rösa. Despite the clear decreases in S 0 2, the visible symptoms of needle tip necroses remained unchanged, especially at the polluted sites Taura and Rösa, although the needles contained higher pigment concentrations than needles from the unpolluted sites. The results of measurements with antioxidants as biomarkers for S 0 2-mediated stress in pine needles show that the adult Scots pine trees at the polluted sites suffered from greater oxidative stress than the needles from the less polluted site.