ON THE PHYSIOLOGICAL SIGNIFICANCE OF DARK REVERSION OF PHYTOCHROME IN THE MUSTARD SEEDLING |
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Authors: | H Oelze-Karow E Scháfer H Mohr |
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Institution: | Biological Institute II, University of Freiburg, 78 Freiburg, Germany |
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Abstract: | Abstract —We present physiological evidence using the threshold control of lipoxygenase synthesis† by Pfr in the mustard seedling (LOG response) that there is no dark reversion of phytochrome which would be relevant for this response. Such Ptr which can be detected with the lipoxygenase response disappears exclusively through degradation with a half-life of 45 min at 25°C. De novo synthesis of P*r in the hypocotylar hook takes place at a constant rate (zero order rate constant) irrespective of the level of Pr or P*tot, i.e. there is no detectable feedback control of Pr synthesis during the period of experimentation. The data of the present paper are consistent with a quantitative phytochrome model (Scheme 1) which has been advanced and treated quantitatively in the companion paper (Oelze-Karow and Mohr, 1976). |
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