Antioxidant defense and physiological gas-exchange responses in ozone-exposed Pinus taeda L
Controlled-field experiments were utilized to evaluate the exposure-response relationships of the chloroplast ascorbate/glutathione hydrogen-peroxide detoxification system and physiological gas-exchange responses in ozone-exposed loblolly pine. Physiological gas-exchange processes included photosynthesis, conductance, transpiration, and intercellular CO{sub 2} concentration (C{sub i}). Biochemical processes include both enzymatic activities and substrate concentrations. Total concentrations of glutathione and ascorbate were measured in both oxidized and reduced forms. Total sulfhydryl content was measured as protein-bound and non protein-bound sulfhydryl concentration. Morphological characteristics, photopigment concentrations, and protein content in needle fascicles were also measured. Cumulative ozone exposure reduced all morphological parameters. Physiologically, ozone decreased photosynthesis, conductance, and transpiration, while slightly increasing C{sub i}. Photopigment concentrations declined with ozone exposure. Biochemically, ozone exposure generally increased the activity of all enzymes but did not appreciably affect substrate concentrations. In a second experiment, photosynthetic rates and glutathione reductase activities were observed in mature loblolly pine trees exposed to ozone. Mature trees responded differently to ozone exposure than did seedlings. Photosynthetic rates in mature trees did not decrease in response to ozone. Glutathione reductase activities in mature trees and seedlings were equivalent.
- Research Organization:
- Duke Univ., Durham, NC (United States)
- OSTI ID:
- 5551574
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
OXIDOREDUCTASES
ENZYME ACTIVITY
OZONE
TOXICITY
PINES
SENSITIVITY
AGE DEPENDENCE
AIR POLLUTION
CHLOROPLASTS
DOSE-RESPONSE RELATIONSHIPS
GLUTATHIONE
PHOTOSYNTHESIS
PLANT GROWTH
TRANSPIRATION
CELL CONSTITUENTS
CHEMICAL REACTIONS
CONIFERS
DRUGS
ENZYMES
GROWTH
ORGANIC COMPOUNDS
PEPTIDES
PHOTOCHEMICAL REACTIONS
PINOPHYTA
PLANTS
POLLUTION
POLYPEPTIDES
PROTEINS
RADIOPROTECTIVE SUBSTANCES
SYNTHESIS
TREES
560300* - Chemicals Metabolism & Toxicology