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Over‐expression of phenol‐oxidising peroxidases alters the UV‐susceptibility of transgenic Nicotiana tabacum
Author(s) -
Jansen Marcel A. K.,
Elfstrand Malin,
Heggie Laura,
Sitbon Folke,
Dix Philip J.,
Thorneley Roger N. 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.1469-8137.2004.01132.x
Subject(s) - peroxidase , nicotiana tabacum , isozyme , biochemistry , biology , nicotiana , horseradish peroxidase , solanaceae , chemistry , enzyme , microbiology and biotechnology , gene
Summary• Class III peroxidases catalyse the oxidative crosslinking of UV‐absorbing phenolics. The effect of changes in the activity of phenol oxidising peroxidases (EC 1.11.1.7) on UV‐tolerance in Nicotiana tabacum plants has been determined. • The UV‐sensitivity of transgenic N. tabacum lines, altered in their peroxidase expression pattern, was studied by measuring radiation effects on photosynthetic efficiency. • Analysis of the effect of UV‐radiation on the relative variable chlorophyll fluorescence showed that the SPI‐2 line, which over‐expresses a defence‐related cationic peroxidase, is markedly UV‐tolerant. By contrast, the ROPN3‐line, which overexpresses a synthetic horseradish peroxidase‐C gene, was found to be UV‐sensitive. The increased activity of indole‐3‐acetic acid (IAA) inducible peroxidases in homozygous IAA‐overproducing transgenic plants was also found to correlate with UV‐sensitivity. • It is concluded that only specific peroxidase isozymes, through their effects on phenolic metabolism, contribute to the UV protection response. Thus, the analysis of the role of isozymes in UV‐protection addresses fundamental questions of isozyme diversity and/or redundancy in relation to phenolic substrates.