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Other factors than apoplastic ascorbate contribute to the differential ozone tolerance of two clones of Trifolium repens L.
Author(s) -
D’HAESE DAVID,
VANDERMEIREN KARINE,
ASARD HAN,
HOREMANS NELE
Publication year - 2005
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2005.01308.x
Subject(s) - apoplast , trifolium repens , clone (java method) , antioxidant , glutathione , chemistry , redox , ozone , reactive oxygen species , biology , botany , horticulture , biochemistry , enzyme , gene , cell wall , organic chemistry
Apoplastic reactive oxygen intermediates, which are formed during the exposure of a higher plant to ozone (O 3 ), have been proposed to be detoxified by apoplastic ascorbate (ASC). An investigation to determine whether the differential sensitivity of two white clover clones ( Trifolium repens L. cv Regal) to O 3 was related with their levels of ASC, glutathione derivatives or with the total antioxidative capacity. In contrast to what might be expected, the sensitive clone of white clover (NC‐S) constitutively showed a 72% higher concentration of apoplastic ASC compared to the O 3 ‐tolerant clone (NC‐R). Furthermore, NC‐S also showed a higher redox status of apoplastic ASC. These results indicate that higher ASC levels in the apoplast of NC‐S are not sufficient to induce a higher O 3 tolerance. The redox status, but not the absolute concentration of homoglutathione in the symplast was found to be constitutively higher in NC‐R than in NC‐S. It is not clear, however, whether homoglutathione is a direct cause of the differential O 3 detoxification capacity of both clones. Total antioxidative capacity measurements ruled out the contribution of other low‐molecular antioxidants to the relative tolerance of NC‐R. It was concluded that elevated apoplastic ASC levels can not always be sufficient to render a plant O 3 tolerant.