caa a22 4500 477101577 CHVBK 20180405111543.0 cr unu---uuuuu 170330e19960701xx s 000 0 eng 10.1007/BF00195728 doi (NATIONALLICENCE)springer-10.1007/BF00195728 Short-term modulation of nitrate reductase activity by exogenous nitrate in Nicotiana plumbaginifolia and Zea mays leaves [Elektronische Daten] [Sylvie Ferrario, Marie-Héléne Valadier, Christine Foyer] Maize (Zea mays L.) grown on low (0.8 mM) NO 3 - , as well as untransformed and transformed Nicotiana plumbaginifolia constitutively expressing nitrate reductase (NR), was used to study the effects of NO 3 - on the NR activation state. The NR activation state was determined from the relationship of total activity extracted in the presence of ethylenediaminetetracetic acid to that extracted in the presence of Mg2+. Light activation was observed in both maize and tobacco leaves. In the tobacco lines, NO 3 - did not influence the NR activation state. In excised maize leaves, no correlation was found between the foliar NO 3 - content and the NR activation state. Similarly, the NR activation state did not respond to NO 3 - . Since the NR activation state determined from the degree of Mg2+-induced inhibition of NR activity is considered to reflect the phosphorylation state of the NR protein, the protein phosphatase inhibitor microcystin LR was used to test the importance of protein phosphorylation in the NO 3 - -induced changes in NR activity. In-vivo inhibition of endogenous protein phosphatase activity by microcystin-LR decreased the level of NR activation in the light. This occurred to the same extent in the presence or absence of exogenous NO 3 - . We conclude that NO 3 - does not effect the NR activation state, as modulated by protein phosphorylation in either tobacco (a C3 species) or maize (a C4 species). The short-term regulation of NR therefore differs from the NO 3 - -mediated responses observed for phosphoenolpyruvate carboxylase and sucrose phosphate synthase. Springer-Verlag, 1996 Nicotiana (nitrate reductase) nationallicence Nitrate nationallicence Nitrate reductase (activation state) nationallicence Protein phosphorylation nationallicence Transgenic plants nationallicence Zea (nitrate reductase) nationallicence Chl : chlorophyll nationallicence MC : microcystin-LR nationallicence PEP-Case : phosphoenolpyruvate carboxylase nationallicence SPS : sucrose-phosphate synthase nationallicence Ferrario Sylvie Laboratoire du Metabolisme, INRA, Route de Saint-Cyr, F-78026, Versailles cedex, France aut Valadier Marie-Héléne Laboratoire du Metabolisme, INRA, Route de Saint-Cyr, F-78026, Versailles cedex, France aut Foyer Christine IGER, Plas Gogerddan, Environmental Biology Department, SY23 3EB, Aberystwyth, Dyfed, UK aut Planta Springer-Verlag 199/3(1996-07-01), 366-371 0032-0935 199:3<366 1996 199 425 https://doi.org/10.1007/BF00195728 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00195728 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ferrario Sylvie Laboratoire du Metabolisme, INRA, Route de Saint-Cyr, F-78026, Versailles cedex, France aut NATIONALLICENCE 700 1- Valadier Marie-Héléne Laboratoire du Metabolisme, INRA, Route de Saint-Cyr, F-78026, Versailles cedex, France aut NATIONALLICENCE 700 1- Foyer Christine IGER, Plas Gogerddan, Environmental Biology Department, SY23 3EB, Aberystwyth, Dyfed, UK aut NATIONALLICENCE 773 0- Planta Springer-Verlag 199/3(1996-07-01), 366-371 0032-0935 199:3<366 1996 199 425 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer