title: Hydrogen peroxide- and nitric oxide-induced systemic antioxidant prime-like activity under NaCl-stress and stress-free conditions in citrus plants.
abstract: We tested whether pre-treatments of roots with H(2)O(2) (10mM for 8h) or sodium nitroprusside (SNP; 100microM for 48h), a donor of ()NO, could induce prime antioxidant defense responses in the leaves of citrus plants grown in the absence or presence of 150mM NaCl for 16d. Both root pre-treatments increased leaf superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) activities, and induced related-isoform(s) expression under non-NaCl-stress conditions. When followed by salinity, certain enzymatic activities also exhibited an up-regulation in response to H(2)O(2) or SNP pre-exposure. An NaCl-stress-provoked decrease in the ascorbate redox state was partially prevented by both pre-treatments, whereas the glutathione redox state under normal and NaCl-stress conditions was increased by SNP. Real-time imaging of ()NO production was found in vascular tissues and epidermal cells. Furthermore, NaCl-induced inhibition in ()OH scavenging activity and promotion of ()OH-mediated DNA strand cleavage was partially prevented by SNP. Moreover, NaCl-dependent protein oxidation (carbonylation) was totally reversed by both pre-treatments as revealed by quantitative assay and protein blotting analysis. These results provide strong evidence that H(2)O(2) and ()NO elicit long-lasting systemic primer-like antioxidant activity in citrus plants under physiological and NaCl-stress conditions.
authors.affiliation: Aristotle University of Thessaloniki, Department of Agriculture, Laboratory of Agricultural Chemistry, University Campus, 54124 Thessaloniki, Greece.
authors.forename: Georgia
authors.initials: G
authors.lastname: Tanou
authors.forename: Athanassios
authors.initials: A
authors.lastname: Molassiotis
authors.forename: Grigorios
authors.initials: G
authors.lastname: Diamantidis
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D002957:Citrus / Q000187:drug effects* / Q000378:metabolism; D016166:Free Radical Scavengers / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology*; D010084:Oxidation-Reduction; D010940:Plant Proteins / Q000378:metabolism*; D012965:Sodium Chloride / Q000378:metabolism*; D013312:Stress, Physiological
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D020030:Nitric Oxide Donors; D010940:Plant Proteins; D009599:Nitroprusside; D012965:Sodium Chloride; D006861:Hydrogen Peroxide