Wingsle G, Strand M, Karpinski S, Hallgren JE
Influence of So2 and No2 Exposure on Antioxidants and Photosynthesis in Needles of Pinus-Sylvestris
Phyton-Annales Rei Botanicae: 1992 32:147-153
Scots pine (Pinus sylvestris L.) trees were exposed from June to October in an open air exposure system to SO2 and NO2 for four years in northern Sweden. Low concentrations of SO2 and NO2 did not change the levels of Vitamin E or pigments in the needles. The reduced glutathione level in the exposed needles was not significantly different from the controls. Although, there was a slight increase in mRNA for superoxide dismutase, enzyme activity did not show any concomitant increase. The observed increase in CuZn SOD mRNA, both in chloroplasts and in cytosol, was not due to a general increase in mRNA of the cells. There were several after-effects even of low concentrations of air SO2 and NO2 under natural conditions. This was evident from a lower light- and CO2-saturated rate of oxygen evolution, a lower photochemical efficiency of photosystem II and a reduced activity of glutathione reductase in needles of exposed trees. The results suggest that the winter might be a critical period for trees exposed to SO2 and NO2.
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