Enzymological study on inorganic nitrogen assimilation during redifferentiation of moss cells

点击翻译按钮获取中文摘要

In recent years, we have established cell suspension cultures from the mosses, Barbula Unguiculata (Takio et al, 1986), Sphagnum imbricatum (Kajita et al. 1987) and Hedwigia ciliata (Takami and Takio 1987), the liverworts, Marchantia paleacea var. diptera (Takio et al. 1988) and Heteroscyphus beschesellei (Takami and Takio 1987), and the hornwort, Anthoceros punctatus (Takami et al. 1988). In contrast to cultures cells from higher plants, cell of most bryophyte species could not grow in a medium containing nitrate as the sole nitrogen source, while their parental or redifferentiated plants could grow in this medium. In order to elucidate the relatioship between differentiation and nitrogen metabolism, in vitro activities of nitrogen assimilating enzymes were determined during redifferentiation of S. imbricatum cells into whole plants.Appropriste conditions for measuring the activities of nitrate reductase (NaR), glutamine synthetase (GS), glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH) were determined in extraxts from suspension cultured cells of S. imbricatum. Pyridine nucleotide specificity and appropriate pH of GDH from S. imbricatum cells were different from those of other plant species. Catalytic properties of NaR, GS and GOGAT from S. imbricatum were similar to those from other plants.Activities of GS, GOGAT and GDH were determined in extracts from callus cells and redifferentiated plantlets. There was no difference in activities of GS, GOGAT between both extracts. High activity of GDH was detected in extracts from callus cells, while no activity was observed in that from plantlets.