Wingsle G, Mattson A, Ekblad A, Hallgren JE, Selstam E
Activities of Glutathione-Reductase and Superoxide-Dismutase in Relation to Changes of Lipids and Pigments Due to Ozone in Seedlings of Pinus-Sylvestris (L)
Plant Science: 1992 82:167-178
Scots pine seedlings (Pinus sylvestris L.) were exposed to ozone at a high-level, 300 ppb 8 h/day for 5 days, and at a low-level, 70-80 ppb 8 h/day for 10 days. In the high-level and low-level experiment the chlorophyll a content decreased 11% and 8%, respectively. The high-level ozone experiment affected the xanthophyll cycle by a 19% higher level of violaxanthin in the exposed seedlings compared to controls at day 5. This was also accompanied by a 42% lower concentration of zeaxanthin. No significant changes of the carotenoids neoxanthin, lutein, alpha-carotene or beta-carotene were found. The molar ratio monogalactosyl diacylglycerol/digalactosyl diacylglycerol decreased by 11% in the high-level ozone exposure. This suggests that the galactolipid:galactolipid galactosyl transferase, located in the outer envelope membrane of the chloroplast, was stimulated by ozone. No significant changes in the total membrane lipid or the acyl group composition was detected. In the high-level ozone experiment the concentration of soluble protein increased in the exposed seedlings during the last 3 days of the experimental period without any change in total protein. No visible damages were observed. The results showed that the activity of the defence enzymes superoxide dismutase (EC 1.15.1.1) and glutathione reductase (EC 1.6.4.2) was not altered after ozone exposure.
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