Seasonal variation in the antioxidant system of eastern white pine needles: evidence for thermal dependence

Antioxidant metabolites in eastern white pine (Pinus strobus L.) needles increased two- to fourfold from the summer to the winter season. Antioxidant enzymes in needle tissue increased between 2- and 122-fold during this same period. These seasonal changes were determined by monitoring ascorbate and...

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Bibliographic Details
Published in:Plant physiology (Bethesda) 1992-02, Vol.98 (2), p.501-508
Main Authors: Anderson, J.V. (University of Florida, Gainesvile, FL), Chevone, B.I, Hess, J.L
Format: Article
Language:English
Subjects:
Acclimatization
ACTIVIDAD ENZIMATICA
ACTIVITE ENZYMATIQUE
ANTIOXIDANTES
Antioxidants
ANTIOXYDANT
COMPOSICION QUIMICA
COMPOSITION CHIMIQUE
Enzymes
FEUILLE
HOJAS
Low temperature
METABOLITE
METABOLITOS
OXIDORREDUCTASAS
OXYDOREDUCTASE
Pine trees
PINUS
PINUS STROBUS
Plants
Protein isoforms
Seasons
Summer
TEMPERATURA
TEMPERATURE
VARIACION ESTACIONAL
VARIATION SAISONNIERE
Winter
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Summary:Antioxidant metabolites in eastern white pine (Pinus strobus L.) needles increased two- to fourfold from the summer to the winter season. Antioxidant enzymes in needle tissue increased between 2- and 122-fold during this same period. These seasonal changes were determined by monitoring ascorbate and glutathione concentrations and the activity of ascorbate peroxidase, glutathione reductase (GR), and superoxide dismutase. Levels of antioxidant metabolites and enzymes were observed always to be lowest during the summer, or active growing season, and highest during the winter, or dormant season. These data correlated well with the thermal kinetic window for purified GR obtained from summer needles. The minimum, apparent Km,NADPH for two isoforms of GR (GRA and GRB) occurred at 5 and 10 degrees C, respectively. The upper limit of the thermal kinetic window (200% of the minimum Km) for GRA and GRB was 20 and 25 degrees C, respectively, indicating that needle temperatures exceeding 25 degrees C may result in impairment of antioxidant metabolism. The needle content and kinetic properties of GR, the increased activities of other enzymes, and the high substrate concentrations observed during the winter are consistent with the protective function this pathway may provide against photooxidative, winter injury
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.98.2.501