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Title: Adaptation of selected plants to ammonium as nitrogen source
Author: Meade, Roger
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 1982
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Nitrogen is one of the major requirements for plant growth, plentiful in some habitats, though scarce in others. A selection of plants from mires, with an emphasis on bryophytes, was examined for possible adaptations to an ammonium-based nutrition at the level of the assimilating enzymes. Measurements of nitrogen-sources in a valley mire demonstrated the presence of both nitrate and ammonium, and either could be used by the component bryophytes. Levels of about O.05mr.contrasted sharply with those of eutrophic habitats , ammonium approaching 1 m in a sewage works discharge. The ammonium-assimilating enzymes glutamate dehydrogenase , glutamine synthetase, and glutamate synthase were found in all genera except Sphagnum, where glutamate dehydrogenase could not be detected. The availability of nitrogen in Sphagnum-dominated habitats was not demonstrably less than environments occupied by genera possessing this enzyme. Levels of some ammonium-assimilating enzymes responded to the amount of substrate supplied within the overall constraints of the culture systems, although behaviour was not characteristic for plants of particular habitats. The affinity of glutamate dehydrogenase and glutamine synthesese for ammonium was similar in species from contrasting habitats. Glutamate dehydrogenase showed a negative cooperative effect with ammonium and some Km values were not incompatible with a role in ammonium assimilation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available