scholarly journals Symbiotic nitrogen fixation and nitrogen budget of Brazilian soybean [Glycine max (L.) Merril] varieties introduced in Benin using 15N isotopic dilution method

2016 ◽  
Vol 11 (1) ◽  
pp. 7-15 ◽  
Author(s):  
C ZOUNDJI Charlotte ◽  
HOUNGNANDAN Pascal ◽  
A KOUELO F eacute lix ◽  
E BOKO Frechno ◽  
J ADU GYAMFI Joseph
Keyword(s):  
Nitrogen Fixation ◽  
Glycine Max ◽  
Symbiotic Nitrogen Fixation ◽  
Nitrogen Budget ◽  
Isotopic Dilution ◽  
Dilution Method ◽  
Isotopic Dilution Method ◽  
Glycine Max L

Metabolite Regulation of Phosphenolpyruvate Carboxylase in Legume Root Nodules

1996 ◽  
Vol 23 (4) ◽  
pp. 413 ◽  
Author(s):  
KC Woo ◽  
S Xu
Keyword(s):  
Nitrogen Fixation ◽  
Glycine Max ◽  
Vigna Unguiculata ◽  
Symbiotic Nitrogen Fixation ◽  
Feedback Inhibition ◽  
Root Nodules ◽  
Psophocarpus Tetragonolobus ◽  
Glycine Max L ◽  
Fructose 1,6 Bisphosphate ◽  
Metabolite Regulation

The effects of metabolic activators and inhibitors on phosphoenolpyruvate carboxylase (PEPC) activity were examined at pH 7 in partially purified enzyme from nodules of soybean (Glycine max (L.) Merr.), Psophocarpus tetragonolobus DC. and Vigna unguiculata ssp. sesquipedalis (L.) Verdc. Glucose 6-phosphate, fructose 6-phosphate, glucose 1-phosphate, fructose 1-phosphate, fructose 1,6- bisphosphate and phosphoglycerate stimulated the activity about 2-fold at low (0.5 mM) but not saturating (2.5 mM) PEP concentration. Glc 6-P and fru 6-P were the most effective activators and they increased the affinity of the enzyme for PEP by 2-4-fold. The dicarboxylates, malate, succinate, malonate, 2-oxoglutarate and aspartate inhibited PEPC activity. Malate was the most inhibitory, and strongly inhibited PEPC activity even at saturating PEP concentration. The Ki values for malate were 0.3-0.4 mM for soybean and P. tetragonolobus. However, glc 6-P and fru 6-P alleviated maiate inhibition and increased the Ki values by 11- to 28-fold in these two species. We propose that glc 6-P (fru 6-P) activates PEPC in a feedforward regulation and protects it against feedback inhibition by malate and thus coordinates the supply of photosynthate availability with malate synthesis required by the bacteroids to support symbiotic nitrogen fixation in nodules.

Evaluation of isotopic dilution method for measuring N2fixation in Azolla: Comparison with other methods1

1989 ◽  
Vol 12 (3) ◽  
pp. 341-362 ◽  
Author(s):  
R. N. Sah ◽  
S. S. Goyal ◽  
D. W. Rains ◽  
D. F. Paige
Keyword(s):  
Isotopic Dilution ◽  
Dilution Method ◽  
Isotopic Dilution Method
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