ISHS Acta Horticulturae 381: International Symposium on Natural Phenols in Plant Resistance
PHENYLPROPANOID METABOLISM OF SPHAGNUM AND NUTRIENT STRESS |
| Author: | S. Rasmussen |
| Keywords: | continuous feed bioreactors, sphagnum acid, hydroxybutenolide, phenol excretion, endogenous free water-soluble phenolics, PAL |
| Abstract:
Sphagnum acid and sphagnum acid derivatives are characteristic cell wall constituents of all Sphagnum species investigated. Furthermore some species, e.g. S. fallax and S. cuspidatum, are characterized by a high content of endogenous free water-soluble phenolics and a pronounced excretion of these phenolic compounds into the external medium. The technique to cultivate Sphagnum axenically in continuous feed bioreactors was used to study some aspects of the phenylpropanoid metabolism without any interference of microorganisms. An enhanced N-supply and an increased nutrient solution flowrate induced a transient stimulation of sphagnum acid excretion in S. fallax. In batch-cultures exogenously supplied phenylalanine (10-4 M) was taken up by 80% within the first 90 min. As a consequence the level especially of free endogenous sphagnum acid and t-cinnamic acid increased dramatically. There was no significant influence on free endogenous p-coumaric acid. This cinnamic acid is, apart from sphagnum acid, primarily excreted. Though the synthesis of phenylpropanoid pathway intermediates was stimulated by the supply of phenylalanine, extractable PAL activity decreased. | |
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