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Ozone‐induced H 2 O 2 accumulation in field‐grown aspen and birch is linked to foliar ultrastructure and peroxisomal activity
Author(s) -
Oksanen E.,
Häikiö E.,
Sober J.,
Karnosky D. F.
Publication year - 2004
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2003.00981.x
Subject(s) - apoplast , ultrastructure , chloroplast , peroxisome , biology , cell wall , catalase , botany , ozone , rubisco , oxidative stress , salicaceae , cytosol , photosynthesis , biochemistry , chemistry , woody plant , enzyme , gene , organic chemistry
Summary• Saplings of three aspen ( Populus tremuloides ) genotypes and seedlings of paper birch ( Betula papyrifera ) were exposed to elevated ozone (1.5× ambient) and 560 p.p.m. CO 2 , singly and in combination, from 1998 at the Aspen‐FACE (free‐air CO 2 enrichment) site (Rhinelander, USA). • The plants were studied for H 2 O 2 accumulation within the leaf mesophyll, number of peroxisomes, level of gene expression for catalase ( Cat ), and changes in ultrastructure. • In tolerant clones, ozone‐elicited excess H 2 O 2 production was restricted to the apoplast, without any ultrastructural injuries. This was associated with ozone‐induced proliferation of peroxisomes and increased transcript levels of Cat . In sensitive plants, ozone‐induced H 2 O 2 accumulation continued from the cell wall to the plasma membrane, cytosol and chloroplasts, particularly in older leaves. However, chloroplastic precipitation was absent in the presence of elevated CO 2 . In the most sensitive aspen clone, H 2 O 2 accumulation was found in conjunction with chloroplast injuries, low number of peroxisomes and low cell wall volume, whereas in birch a simultaneous increase in cell wall thickness indicated defence activation. • Our results indicate that oxidative stress manifests as H 2 O 2 effects on leaf ultrastructure in sensitive trees exposed to elevated ozone. However, CO 2 enrichment appears to alleviate chloroplastic oxidative stress.