Nitrogen uptake regulation

Ureases [27] Niai)-Niai) Hydrolysis of urea Treatment of bacterial infections, regulation of nitrogen uptake in plants... 

Growth regulators can influence a plant s absorption of minerals from the soil. The uptake of potassium by wheat, for example, is accelerated by treating the plant with gibberellic acid. The uptake of both nitrogen and phosphorus by wheat and soybean plants is enhanced by treatment with 2,4-D. 

Diacetyl, and its reduction products, acetoin and 2,3-butanediol, are also derived from acetaldehyde (Fig 8D.7), providing additional NADH oxidation steps. Diacetyl, which is formed by the decarboxylation of a-acetolactate, is regulated by valine and threonine availability (Dufour 1989). When assimilable nitrogen is low, valine synthesis is activated. This leads to the formation of a-acetolactate, which can be then transformed into diacetyl via spontaneous oxidative decarboxylation. Because valine uptake is suppressed by threonine, sufficient nitrogen availability represses the formation of diacetyl. Moreover, the final concentration of diacetyl is determined by its possible stepwise reduction to acetoin and 2,3-butanediol, both steps being dependent on NADH availability. Branched-chain aldehydes are formed via the Ehrlich pathway (Fig 8D.7) from precursors formed by combination of acetaldehyde with pyruvic acid and a-ketobutyrate (Fig 8D.7). 

Fujita, R. M. (1985). The role of nitrogen status in regulating transient ammonium uptake and nitrogen storage by macroalgae. J. Exp. Mar. Biol. Ecol. 92, 283—301. 

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