Roles of nitrate, nitrite and ammonium ion in phytochrome regulation of nitrate reductase gene expression in maize

Raghuram, Nandula ; Sopory, Sudhir K. (1999) Roles of nitrate, nitrite and ammonium ion in phytochrome regulation of nitrate reductase gene expression in maize IUBMB Life, 47 (2). pp. 239-249. ISSN 1521-6543

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Official URL: http://onlinelibrary.wiley.com/doi/10.1080/1521654...

Related URL: http://dx.doi.org/10.1080/15216549900201253

Abstract

The influence of nitrate and its metabolites on the nitrate reductase (NR) gene expression and its relationship with phytochrome (Pfr) regulation of NR in etiolated maize leaves is examined. Nitrate induction and Pfr stimulation are brought about by independent signalling phenomena. Phorbol myristate acetate (PMA), a stimulator of protein kinase C (PKC), mimicked the effect of red light but could not replace the nitrate requirement for the induction of NR transcript accumulation. This suggests that while PKC-type enzymes may be involved in mediating the Pfr signal, nitrate may follow an independent signalling mechanism. Experiments with 5-hydroxytryptamine (5HT) and lithium ions (Li+), which are known to modulate phosphoinositide (PI) turnover, indicated that in addition to generating Pfr-induced second messengers for PKC activation, PI cycle may also generate other signals which mediate nitrate induction of NR gene expression in the dark. The products of nitrate reduction ie, nitrite and ammonium ion had inhibitory and stimulatory effects respectively, on NR transcript accumulation. They work mainly at the level of nitrate induction.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons.
Keywords:Nitrate Reductase; Phytochrome; Signal Transduction; PI Cycle; PKC; PMA; 5HT; Lithium; Zea mays
ID Code:49860
Deposited On:21 Jul 2011 09:27
Last Modified:21 Jul 2011 09:27

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