Hofer Nora, Alexou Maria, Heerdt Christian, Löw Markus, Werner Herbert, Matyssek Rainer, Rennenberg Heinz, Haberer Kristine
Institute of Forest Botany and Tree Physiology, Chair of Tree Physiology, Albert-Ludwigs-University, Georges-Köhler-Allee 053/054, D-79110 Freiburg, Germany.
Environ Pollut. 2008 Jul;154(2):241-53. doi: 10.1016/j.envpol.2007.10.005. Epub 2007 Nov 26.
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 (2xO3), 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.
