Abstract

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

Keywords

UV-radiation; auxin; stress; peroxidase; chlorophyll a fluorescence; Nicotiana tabacum (tobacco)

Published in

New Phytologist
2004, Volume: 163, number: 3, pages: 585-594
Publisher: BLACKWELL PUBLISHING LTD

SLU Authors

• Elfstrand, Malin

  • Department of Plant Biology, Swedish University of Agricultural Sciences
    

• Sitbon, Folke

  • Department of Plant Biology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Biochemistry and Molecular Biology


Publication identifier

DOI: https://doi.org/10.1111/j.1469-8137.2004.01132.x

Permanent link to this page (URI)

https://res.slu.se/id/publ/3702