Photosynthetic production of hydrogen peroxide by Ulva rigida C. Ag. (Chlorophyta) |
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Authors: | Jonas Collén Miguel Jiménez Del Rio Guillermo García-Reina Marianne Pedersén |
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Institution: | (1) Department of Physiological Botany, Uppsala University, Villavägen 6, S-752 36 Uppsala, Sweden;(2) Institute of Applied Algology, Instituto Tecnológico de Canarias, Box 550, Las Palmas de Gran Canaria, Spain |
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Abstract: | Production of hydrogen peroxide has been found in Ulva rigida (Chlorophyta). The formation of H2O2 was light dependent with a production of 1.2 mol·g FW–1·h–1 in sea water (pH 8.2) at an irradiance of 700 mol photons m–2·s–1. The excretion was also pH dependent: in pH 6.5 the production was not detectable (< 5 nmol·g FW–1·h–1) but at pH 9.0 the production was 5.0 mol·g FW–1·h–1. The production of H2O2 was totally inhibited by 3-(3,4-dichlorophenyl)-1,1 dimethylurea (DCMU). The ability of U. rigida growing in tanks (7501) under a natural light regime to excrete H2O2 was checked and found to be seven times higher at 08.00 hours than other times of the day. The H2O2 concentration in the cultivation tank (density: 2 g FW·l–1) reached the highest value (3 M) at 11.00 hours. Photosynthesis was not influenced by H2O2 formation. The H2O2 is suggested to come from the Mehler reaction (pseudocyclic photophosphorylation). With an oxygen evolution of 120 mmol·g FW–1·h–1 at pH 8.2 and 90 mmol·g FW–1·h–1 at pH 9.0, 0.5% and 2.7% of the electrons were used for extracellular H2O2 production. The H2O2 production is sufficiently high to be of physiological and ecological significance, and is suggested to be a part of the defence against epi and endophytes.Abbreviations ACL
artificial, continuous light
- DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- GNL
greenhouse
- LDC
Luminol-dependent chemiluminescence
- SOD
Superoxide dismutase
This investigation was supported by SAREC (Swedish Agency for Research Cooperation with Developing Countries), Hierta-Retzius Foundation, Marianne and Marcus Wallenberg Foundation, the Swedish Environmental Protection Board, and CICYT Spain. |
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Keywords: | Chemical defence Hydrogen peroxide Mehler reaction Photosynthesis Ulva |
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