title: Gas exchange and antioxidative compounds in young beech trees under free-air ozone exposure and comparisons to adult trees.
abstract: Three-year-old beech (Fagus sylvatica) seedlings growing in containers were placed into the sun and shade crown of a mature beech stand exposed to ambient (1 x O(3)) and double ambient (2 x O(3)) ozone concentrations at a free-air exposure system ("Kranzberg Forst", Germany). Pigments, alpha-tocopherol, glutathione, ascorbate, and gas exchange were measured in leaves during 2003 (a drought year) and 2004 (an average year). Sun-exposed seedlings showed higher contents of antioxidants, xanthophylls, and beta-carotene and lower contents of chlorophyll, alpha-carotene, and neoxanthin than shade-exposed seedlings. In 2003 sun-exposed seedlings showed higher contents of carotenoids and total glutathione and lower net photosynthesis rates (A(max)) compared to 2004. O(3) exposure generally affected the content of chlorophyll, the xanthophyll cycle, and the intercellular CO(2) concentration (c(i)). Seedlings differed from the adjacent adult trees in most biochemical and physiological parameters investigated: Sun exposed seedlings showed higher contents of alpha-tocopherol and xanthophylls and lower contents of ascorbate, chlorophyll, neoxanthin, and alpha-carotene compared to adult trees. Shade exposed seedlings had lower contents of xanthophylls, alpha-carotene, and alpha-tocopherol than shade leaves of old-growth trees. In 2003, seedlings had higher A(max), stomatal conductance (g(s)), and c(i) under 2 x O(3) than adult trees. The results showed that shade acclimated beech seedlings are more sensitive to O(3), possibly due to a lower antioxidative capacity per O(3) uptake. We conclude that beech seedlings are uncertain surrogates for adult beech trees.
authors.affiliation: Institut für Pflanzenwissenschaften, Universität Graz, Schuberstrasse 51, 8010 Graz, Austria. karin.herbinger@uni-graz.at
authors.forename: K
authors.initials: K
authors.lastname: Herbinger
authors.forename: C
authors.initials: C
authors.lastname: Then
authors.forename: K
authors.initials: K
authors.lastname: Haberer
authors.forename: M
authors.initials: M
authors.lastname: Alexou
authors.forename: M
authors.initials: M
authors.lastname: Löw
authors.forename: K
authors.initials: K
authors.lastname: Remele
authors.forename: H
authors.initials: H
authors.lastname: Rennenberg
authors.forename: R
authors.initials: R
authors.lastname: Matyssek
authors.forename: D
authors.initials: D
authors.lastname: Grill
authors.forename: G
authors.initials: G
authors.lastname: Wieser
authors.forename: M
authors.initials: M
authors.lastname: Tausz
mesh_terms: D000388:Air; D000704:Analysis of Variance; D000975:Antioxidants / Q000378:metabolism*; D001205:Ascorbic Acid / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D029964:Fagus / Q000187:drug effects* / Q000378:metabolism*; D005740:Gases / Q000378:metabolism*; D010126:Ozone / Q000494:pharmacology*; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism; D014197:Trees / Q000187:drug effects / Q000378:metabolism; D024341:Xanthophylls / Q000378:metabolism
chemical_list: D000975:Antioxidants; D005740:Gases; D024341:Xanthophylls; D002734:Chlorophyll; D010126:Ozone; D001205:Ascorbic Acid