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Enzymes of ammonium metabolism in ectendomycorrhizal and ectomycorrhizal symbionts of pine
Author(s) -
Rudawska Maria,
KieliszewskaRokicka Barbara,
Debaud JeanClaude,
Lewandowski Andrzej,
Gay Gilles
Publication year - 1994
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1994.tb05338.x
Subject(s) - glutamine synthetase , glutamate dehydrogenase , glutamate synthase , ammonium , biology , nitrogen assimilation , biochemistry , mycelium , ectomycorrhiza , assimilation (phonology) , enzyme , metabolism , glutamine , fungus , botany , symbiosis , mycorrhiza , glutamate receptor , bacteria , chemistry , amino acid , philosophy , receptor , organic chemistry , genetics , linguistics
Ammonium assimilation enzymes from several strains of ectendo‐ and ectomycorrhizal fungi were assayed after three weeks culture on a buffered synthetic medium containing ammonium as sole nitrogen source. Activity of NADP‐dependent glutamate dehydrogenase (GDH, EC 1.4.1.4) of ectomycorrhizal strains was very low despite excellent mycelial growth. Only ectendomycorrhizal fungus MrgX isolated from roots of Pinus sylvestris showed high GDH activity. Similar results were obtained when the enzyme extracts were subjected to starch gel electrophoresis. Growth of the fungi, except ectendomycorrhizal MrgX, was arrested when inhibitors of glutamine synthetase (GS, EC 6.3.1.2) or glutamate synthase (GOGAT. EC 1.4.7.1) (methionine sulphoximine or albizine, respectively) were included in the culture medium. Glutamine synthetase activity was found in all fungi tested. The results suggest that the GS pathway for ammonium assimilation is potentially operative in ectomycorrhizal fungi and imply only a minor role for GDH in ammonium assimilation by the studied ectomycorrhizal symbionts of pine. Some physiological and ecological implications of these results are discussed.