Seasonal differences and within-canopy variations of antioxidants in mature spruce ( Picea abies) trees under elevated ozone in a free-air exposure system

• Published in: Environmental pollution (1987) 2008-07, Vol.154 (2), p.241-253
• Main Authors: Hofer, Nora, Alexou, Maria, Heerdt, Christian, Löw, Markus, Werner, Herbert, Matyssek, Rainer, Rennenberg, Heinz, Haberer, Kristine
• Format: Article
• Language: English
• Subjects: Air Pollutants - toxicity; Animal, plant and microbial ecology; antioxidant activity; Antioxidants; Antioxidants - analysis; Applied ecology; ascorbic acid; Biological and medical sciences; Canopy position; chemical constituents of plants; drought; Ecology - methods; Ecotoxicology, biological effects of pollution; elevated atmospheric gases; forest trees; Free-air ozone fumigation; Fundamental and applied biological sciences. Psychology; General aspects; Germany; glutathione; Glutathione - analysis; intercellular spaces; leaves; Oxidation-Reduction; ozone; Ozone - toxicity; phloem; Picea - chemistry; Picea abies; Plant Leaves - chemistry; Plant Shoots - chemistry; Rain; sap; seasonal variation; Seasons; spatial variation; Summer drought; temperate forests; Temperature; tree crown; water stress; xylem
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2007.10.005

The effect of free-air ozone fumigation and crown position on antioxidants were determined in old-growth spruce ( Picea abies) trees in the seasonal course of two consecutive years (2003 and 2004). Levels of total ascorbate and its redox state in the apoplastic washing fluid (AWF) were increased under double ambient ozone concentrations (2 × O 3), whilst ascorbate concentrations in needle extracts were unchanged. Concentrations of apoplastic and symplastic ascorbate were significantly higher in 2003 compared to 2004 indicating a combined effect of the drought conditions in 2003 with enhanced ozone exposure. Elevated ozone had only weak effects on total glutathione levels in needle extracts, phloem exudates and xylem saps. Total and oxidised glutathione concentrations were higher in 2004 compared to 2003 and seemed to be more affected by enhanced ozone influx in the more humid year 2004 compared to the combined effect of elevated ozone and drought in 2003 as observed for ascorbate. Antioxidant defence in sun and shade needles of Picea abies under free-air ozone fumigation in the seasonal course of two consecutive years.