Over-expression of phenol-oxidising peroxidases alters the UV-susceptibility of transgenic Nicotiana tabacum

Authors

  • Marcel A. K. Jansen,

    Corresponding author
    1. Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK;
    2. Present address: Department of Plant Sciences (ZEPS), University College Cork, Distillery Field, North Mall, Cork, Ireland;
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  • Malin Elfstrand,

    1. Department of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden;
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  • Laura Heggie,

    1. Institute of Bioengineering and Agroecology, Department of Biology, National University of Ireland, Maynooth, County Kildare, Ireland;
    2. Present address: Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
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  • Folke Sitbon,

    1. Department of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden;
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  • Philip J. Dix,

    1. Institute of Bioengineering and Agroecology, Department of Biology, National University of Ireland, Maynooth, County Kildare, Ireland;
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  • Roger N. F. Thorneley

    1. Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK;
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Author for correspondence: Marcel A. K. Jansen Tel: +353 (0)21 4904558 Fax: +353 (0)21 4251256 Email: M.Jansen@UCC.IE

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.

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