This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Segura-Aguilar, J. Articles by Rydström, J. Search for Related Content PubMed PubMed Citation Articles by Segura-Aguilar, J. Articles by Rydström, J. Agricola Articles by Segura-Aguilar, J. Articles by Rydström, J.

Environmental and Stress Physiology

The Effect of 5OH-1,4-Naphthoquinone on Norway Spruce Seeds during Germination ¹

Unit for Biochemical Toxicology, Department for Biochemistry, Wallenberg Laboratory, Stockholm University, S-106 91 Stockholm, Sweden, Department of Botany, Stockholm University, S-106 91 Stockholm, Sweden, Department for Biochemistry and Biochemical Technology, Kungliga Tekniska Högskolan, S-100 44 Stockholm, Sweden

The effect of 5-OH-1,4-naphthoquinone (5OH-NQ), a known inhibitor of germination and growth and an inducer of oxidative stress, on seeds from Norway spruce (Picea abies) during germination was studied. 5OH-NQ was activated by homogenate from seeds to reactive species that reduce oxygen to superoxide radicals in vitro. Increasing concentrations of 5OH-NQ increased lipid peroxidation during this activation. Small effects of 5OH-NQ on germination of seeds were observed at concentrations up to 200 µM. However, higher concentrations, e.g. 500 and 1000 µM, exerted more pronounced effects on seeds. These results suggest that the effect of 5OH-NQ was a delay rather than an inhibition of germination. However, the effect of 5OH-NQ on postgerminative growth was more potent than that on germination, and higher concentrations inhibited growth >97%. These results suggest that the seeds have a very effective defense system against quinone and reactive oxygen species, since the small effects of 5OH-NQ on germination and postgermination at concentrations up to 200 µM can be explained by the formation of a metabolite of 5OH-NQ that is not as reactive with oxygen as the original quinone. The 5OH-NQ metabolite collected during germination experiments showed differences in its absorption spectrum in comparison with 5OH-NQ, which suggest changes in structure. This metabolite was reduced by quinone reductase, but reduction of oxygen to superoxide radicals was not detected during its activation with homogenate from seeds. This metabolite may arise via a conjugation reaction, since the addition of 500 µM uridine 5'-diphosphoglucuronic acid or 3'-phosphoadenosine-5'-phosphosulfate to the incubation mixture during activation of this metabolite by homogenate from seeds in vitro inhibited reduction of oxygen to superoxide radicals by 50 and 64%, respectively. The constitutive levels of superoxide dismutase and catalase were sufficient to prevent oxygen toxicity during activation of 5OH-NQ, since these enzymes were not induced when the seeds were treated with 200 µM 5OH-NQ.

This article has been cited by other articles:

				G. R. von Kiparski, L. S. Lee, and A. R. Gillespie Occurrence and Fate of the Phytotoxin Juglone in Alley Soils under Black Walnut Trees J. Environ. Qual., April 5, 2007; 36(3): 709 - 717. [Abstract] [Full Text] [PDF]