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Published online by Cambridge University Press: 05 December 2011
We have studied the defences of Norway spruce seeds against pollutants during germination, using two different phenolic compounds, 5-OH-1,4-naphthoquinone (5-OH-NQ)3 and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T).
Only small effects of 5-OH-NQ on germination of seeds were observed at concentrations up to 200 μM, which could be explained by the formation of a less reactive metabolite of 5-OH-NQ. These results suggest that Norway spruce seeds have a very effective defence system against quinone and quinonederived reactive oxygen species.
The effect of 2,4,5-T on seed germination was, however, more pronounced, resulting in an abnormal growth of the seedlings. This behaviour was probably due to a strong increase in ethylene production (10-fold) in these seedlings. Also fatty acyl-CoA oxidase activity, a peroxisomal enzyme of β-oxidation that catalyses the formation of H2O2, was found to increase 6.9-fold in seedlings germinated in presence of 2,4,5-T. A strong decrease in the activity of photosystem II and an increase in lipid peroxidation in chloroplasts was also observed.
The results presented in this paper have been published in part in Plant Physiology 100, 1955–1961 (1992) by Segura-Aguilar, J., Hakman, I. & Rydström, J. In addition, a manuscript entitled ‘Effect of 2,4,5-trichlorophenoxy acetic acid on germinating Norway spruce’ by Segura-Aguilar, J., Hakman, I. & Rydström, J. has been submitted for publication.