Response of photosynthesis and cellular antioxidants to ozone in Populus leaves

Journal Article · Sat Jun 01 00:00:00 EDT 1991 · Plant Physiology; (United States)

DOI:https://doi.org/10.1104/pp.96.2.650· OSTI ID:7110419

Gupta, A S; Alscher, R G ^[1]; McCune, D ^[2]

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1. Virginia Polytechnic Inst. and State Univ., Blacksburg (United States)
2. Cornell Univ., Ithaca, NY (United States)

Atmospheric ozone causes formation of various highly reactive intermediates (e.g. peroxyl and superoxide radicals, H{sub 2}O{sub 2}, etc.) in plant tissues. A plant's productivity in environments with ozone may be related to its ability to scavenge the free radicals formed. The effects of ozone on photosynthesis and some free radical scavengers were measured in the fifth emergent leaf of poplars. Clonal poplars (Populus deltoides {times} Populus cv caudina) were fumigated with 180 parts per billion ozone for 3 hours. Photosynthesis was measured before, during, and after fumigation. During the first 90 minutes of ozone exposure, photosynthetic rates were unaffected but gluthathione levels and superoxide dismutase activity increased. After 90 minutes of ozone exposure photosynthetic rates began to decline while glutathione and superoxide dismutase continued to increase. Total glutathione (reduced plus oxidized) increased in fumigated leaves throughout the exposure period. The ratio of GSH/GSSG also decreased from 12.8 to 1.2 in ozone exposed trees. Superoxide dismutase levels increased twofold in fumigated plants. After 4 hours of ozone exposure, the photosynthetic rate was approximately half that of controls while flutathione levels and superoxide dismutase activity remained above that of the controls. The elevated antioxidant levels were maintained 21 hours after ozone exposure while photosynthetic rates recovered to about 75% of that of controls. Electron transport and NADPH levels remained unaffected by the treatment. Hence, elevated antioxidant metabolism may protect the photosynthetic apparatus during exposure to ozone.

• OSTI ID: 7110419
• Journal Information: Plant Physiology; (United States), Vol. 96:2; ISSN 0032-0889
• Country of Publication: United States
• Language: English

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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
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OZONE
TOXICITY
POPLARS
PHYSIOLOGY
ANTIOXIDANTS
GLUTATHIONE
LEAVES
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ORGANIC COMPOUNDS
OXIDOREDUCTASES
PEPTIDES
PHOTOCHEMICAL REACTIONS
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POLYPEPTIDES
PROTEINS
RADICALS
RADIOPROTECTIVE SUBSTANCES
SYNTHESIS
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