caa a22 4500 469027584 CHVBK 20180323132734.0 cr unu---uuuuu 170328e19920801xx s 000 0 eng 10.1007/BF00232693 doi (NATIONALLICENCE)springer-10.1007/BF00232693 Nitrate use by tobacco cells in response to N-stress and ammonium nutrition [Elektronische Daten] [Ningyan Zhang, Charles MacKown] Summary: Characterization of NO 3 − use by suspension cultured tobacco cells during a culture cycle is needed to take advantage of cell cultures for further study of the biochemical regulation of NO 3 − uptake induction and decay processes. Tobacco (Nicotiana tabacum L., cv. Ky14) cells were cultured with media containing different N sources. Cells cultured with a mixture of NO 3 − and NH 4 + (40 mM NO 3 − plus 20 mM NH 4 + , in Murashige and Skoog media) initially grew slightly faster but attained the same maximum cell culture density as those cultured with 40 mM NO 3 − only. Cells subcultured with N-free media grew at a similar rate for the first 3 d as those cells grown with N, then ceased further growth. The cessation of growth of cells subcultured with N-free media coincided with depletion of cell NO 3 − . The NO 3 − influx of cells subcultured with N-free media increased eleven-fold and those grown with N increased four- to five-fold before declining. Maximal NO 3 − influx rates occurred at the onset of the stationary growth phase for N-stressed cells, while cells grown with N reached maximums prior to the stationary phase of cell growth. Cells grown with a mixture of NO 3 − and NH 4 + had lower NO 3 − reductase (NR) activity and higher cell NO 3 − levels than those of cells grown with NO 3 − only. The NR activity of cells subcultured with N-free media peaked within 1 d after subculture before declining to a constitutive level when cell NO 3 − was depleted. The level of cell NO 3 − plays a critical role in the expression of the NO 3 − uptake and reduction processes. The transitions in the expression of NO 3 − uptake and reduction activities of tobacco cell suspension cultures should prove valuable for further study of the biochemical and molecular basis for the regulation of these processes. Springer-Verlag, 1992 Zhang Ningyan Department of Agronomy, University of Kentucky and USDA-ARS, 40546-0091, Lexington, KY, USA aut MacKown Charles Department of Agronomy, University of Kentucky and USDA-ARS, 40546-0091, Lexington, KY, USA aut Plant Cell Reports Springer-Verlag 11/9(1992-08-01), 470-475 0721-7714 11:9<470 1992 11 299 https://doi.org/10.1007/BF00232693 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00232693 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Zhang Ningyan Department of Agronomy, University of Kentucky and USDA-ARS, 40546-0091, Lexington, KY, USA aut NATIONALLICENCE 700 1- MacKown Charles Department of Agronomy, University of Kentucky and USDA-ARS, 40546-0091, Lexington, KY, USA aut NATIONALLICENCE 773 0- Plant Cell Reports Springer-Verlag 11/9(1992-08-01), 470-475 0721-7714 11:9<470 1992 11 299 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer