Ammonium Assimilation and Metabolism in Rice

2020 ◽  
pp. 211-231
Author(s):  
Soichi Kojima ◽  
Keiki Ishiyama ◽  
Marcel Pascal Beier ◽  
Toshihiko Hayakawa
Keyword(s):  
Ammonium Assimilation

Expression of a ferredoxin-dependent glutamate synthase gene in mesophyll and vascular cells and functions of the enzyme in ammonium assimilation in Nicotiana tabacum (L.)

Planta ◽  
2005 ◽  
Vol 222 (4) ◽  
pp. 667-677 ◽  
Author(s):  
Magali Feraud ◽  
Céline Masclaux-Daubresse ◽  
Sylvie Ferrario-Méry ◽  
Karine Pageau ◽  
Maud Lelandais ◽  
...  
Keyword(s):  
Nicotiana Tabacum ◽  
Glutamate Synthase ◽  
Ammonium Assimilation ◽  
Vascular Cells ◽  
Nicotiana Tabacum L

Over-expression of the rice OsAMT1-1 gene increases ammonium uptake and content, but impairs growth and development of plants under high ammonium nutrition

2006 ◽  
Vol 33 (2) ◽  
pp. 153 ◽  
Author(s):  
Mohammad S. Hoque ◽  
Josette Masle ◽  
Michael K. Udvardi ◽  
Peter R. Ryan ◽  
Narayana M. Upadhyaya
Keyword(s):  
Transgenic Plants ◽  
Ammonium Assimilation ◽  
Ammonium Transporter ◽  
Ammonium Uptake ◽  
Vegetative Stage ◽  
Over Expression ◽  
Transgenic Lines ◽  
Ammonium Nutrition ◽  
Maize Ubiquitin Promoter

A transgenic approach was undertaken to investigate the role of a rice ammonium transporter (OsAMT1-1) in ammonium uptake and consequent ammonium assimilation under different nitrogen regimes. Transgenic lines overexpressing OsAMT1-1 were produced by Agrobacterium-mediated transformation of two rice cultivars, Taipei 309 and Jarrah, with an OsAMT1-1 cDNA gene construct driven by the maize ubiquitin promoter. Transcript levels of OsAMT1-1 in both Taipei 309 and Jarrah transgenic lines correlated positively with transgene copy number. Shoot and root biomass of some transgenic lines decreased during seedling and early vegetative stage compared to the wild type, especially when grown under high (2 mm) ammonium nutrition. Transgenic plants, particularly those of cv. Jarrah recovered in the mid-vegetative stage under high ammonium nutrition. Roots of the transgenic plants showed increased ammonium uptake and ammonium content. We conclude that the decreased biomass of the transgenic lines at early stages of growth might be caused by the accumulation of ammonium in the roots owing to the inability of ammonium assimilation to match the greater ammonium uptake.

Properties of NAD-dependent glutamate dehydrogenase from the tylosin producer Streptomyces fradiae

1997 ◽  
Vol 43 (11) ◽  
pp. 1005-1010 ◽  
Author(s):  
Kien Trung Nguyen ◽  
Lieu Thi Nguyen ◽  
Jan Kopecký ◽  
Vladislav Běhal
Keyword(s):  
Key Words ◽  
Glutamate Dehydrogenase ◽  
Reductive Amination ◽  
Divalent Cations ◽  
Ammonium Assimilation ◽  
Alkaline Ph ◽  
Streptomyces Fradiae ◽  
Oxidative Deamination

Glutamate dehydrogenase is an enzyme responsible for ammonium assimilation and glutamate catabolism in organisms. The tylosin producer Streptomyces fradiae possesses both NADP- and NAD-dependent glutamate dehydrogenases. The latter enzyme was purified 498-fold with a 7.5% recovery by a six-step protocol. The enzyme is composed of two subunits, each of Mr 47 000, and could form active aggregates of four or eight subunits. Its activity was inactivated by alkaline pH or temperatures of −20 °C or above 40 °C. Activities assayed in the direction of oxidative deamination and reductive amination were optimal at pH 9.2 and 8.8, respectively, and at temperatures of 30–35 °C. No activity was found when NAD(H) was replaced with NADP(H). The Km values were 32.2 mM for L-glutamate, 0.3 mM for NAD+, 3.4 mM for 2-ketoglutarate, 14.2 mM for NH4+, and 0.05 mM for NADH. Deamination activity was partially inhibited by adenyl nucleotides and several divalent cations; amination activity was not affected by the nucleotides but significantly inhibited by Cu2+ or Ni2+.Key words: Streptomyces fradiae, NAD-dependent glutamate dehydrogenase, purification, properties.

Preferential nitrate immobilization in alkaline soils

Soil Research ◽  
1992 ◽  
Vol 30 (5) ◽  
pp. 737 ◽  
Author(s):  
IJ Rochester ◽  
GA Constable ◽  
DA Macleod
Keyword(s):  
Acid Soil ◽  
Nitrification Inhibitor ◽  
Biological Significance ◽  
Nitrate Assimilation ◽  
Acid Soils ◽  
Ammonium Assimilation ◽  
Potassium Nitrate ◽  
Alkaline Soil ◽  
Alkaline Soils ◽  
Nitrate Immobilization

The literature pertaining to N immobilization indicates that ammonium is immobilized in preference to nitrate. Our previous research in an alkaline clay soil has indicated substantial immobilization of nitrate. To verify the preference for immobilization of nitrate or ammonium by the microbial biomass in this and other soil types, the immobilization of ammonium and nitrate from applications of ammonium sulfate and potassium nitrate following the addition of cotton crop stubble was monitored in six soils. The preference for ammonium or nitrate immobilization was highly correlated with each soil's pH, C/N ratio and its nitrification capacity. Nitrate was immobilized in preference to ammonium in neutral and alkaline soils; ammonium was preferentially immobilized in acid soils. No assimilation of nitrate (or nitrification) occurred in the most acid soil. Similarly, little assimilation of ammonium occurred in the most alkaline soil. Two physiological pathways, the nitrate assimilation pathway and the ammonium assimilation pathway, appear to operate concurrently; the dominance of one pathway over the other is indicated by soil pH. The addition of a nitrification inhibitor to an alkaline soil enhanced the immobilization of ammonium. Recovery of 15N confirmed that N was not denitrified, but was biologically immobilized. The immobilization of 1 5 ~ and the apparent immobilization of N were similar in magnitude. The identification of preferential nitrate immobilization has profound biological significance for the cycling of N in alkaline soils.

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