title: Responses of antioxidant enzymes to cold and high light are not correlated to freezing tolerance in natural accessions of Arabidopsis thaliana.
abstract: Low temperatures and high light cause imbalances in primary and secondary reactions of photosynthesis, and thus can result in oxidative stress. Plants employ a range of low-molecular weight antioxidants and antioxidant enzymes to prevent oxidative damage, and antioxidant defence is considered an important component of stress tolerance. To figure out whether oxidative stress and antioxidant defence are key factors defining the different cold acclimation capacities of natural accessions of the model plant Arabidopsis thaliana, we investigated hydrogen peroxide (H2 O2 ) production, antioxidant enzyme activity and lipid peroxidation during a time course of cold treatment and exposure to high light in four differentially cold-tolerant natural accessions of Arabidopsis (C24, Nd, Rsch, Te) that span the European distribution range of the species. All accessions except Rsch (from Russia) had elevated H2 O2 in the cold, indicating that production of reactive oxygen species is part of the cold response in Arabidopsis. Glutathione reductase activity increased in all but Rsch, while ascorbate peroxidase and superoxide dismutase were unchanged and catalase decreased in all but Rsch. Under high light, the Scandinavian accession Te had elevated levels of H2 O2 . Te appeared most sensitive to oxidative stress, having higher malondialdehyde (MDA) levels in the cold and under high light, while only high light caused elevated MDA in the other accessions. Although the most freezing-tolerant, Te had the highest sensitivity to oxidative stress. No correlation was found between freezing tolerance and activity of antioxidant enzymes in the four accessions investigated, arguing against a key role for antioxidant defence in the differential cold acclimation capacities of Arabidopsis accessions.
authors.affiliation: Department of Plant Biotechnology, Institute of Biology, University of Stuttgart, Stuttgart, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Distelbarth
authors.forename: T
authors.initials: T
authors.lastname: Nägele
authors.forename: A G
authors.initials: AG
authors.lastname: Heyer
mesh_terms: D000064:Acclimatization; D000975:Antioxidants / Q000032:analysis / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology / Q000502:physiology* / Q000528:radiation effects; D060387:Ascorbate Peroxidases / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D003080:Cold Temperature; D005615:Freezing; D018506:Gene Expression Regulation, Plant; D005980:Glutathione Reductase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000032:analysis / Q000378:metabolism; D008027:Light; D015227:Lipid Peroxidation; D008315:Malondialdehyde / Q000032:analysis / Q000378:metabolism; D018384:Oxidative Stress; D018515:Plant Leaves / Q000201:enzymology / Q000502:physiology / Q000528:radiation effects; D017382:Reactive Oxygen Species / Q000032:analysis / Q000378:metabolism; D013312:Stress, Physiological; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D002734:Chlorophyll; D008315:Malondialdehyde; D006861:Hydrogen Peroxide; D060387:Ascorbate Peroxidases; D002374:Catalase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase
keywords: Antioxidant enzymes; Arabidopsis; high light; low temperature; oxidative stress