Phenotypic reversion of nitrogenase in pleiotropic mutants of Rhizobium meliloti

1979 ◽  
Vol 25 (3) ◽  
pp. 298-301 ◽  
Author(s):  
Ilona Barabás ◽  
Tibor Sik
Keyword(s):  
Amino Acids ◽  
Nitrogen Fixation ◽  
Nitrate Reductase ◽  
Nitrate Reductase Activity ◽  
Symbiotic Nitrogen Fixation ◽  
Rhizobium Meliloti ◽  
Nitrogenase Activity ◽  
Reductase Activity ◽  
Amino Acid Utilization ◽  
Phenotypic Reversion

In two out of three pleiotropic mutants of Rhizobium meliloti, defective in nitrate reductase induced by amino acid utilization in vegetative bacteria and in symbiotic nitrogen fixation, nitrogenase activity could be restored completely by purines and partially by the amino acids L-glutamate, L-aspartate, L-glutamine, and L-asparagine. The compounds restoring effectiveness in nitrogen fixation did not restore nitrate reductase activity in vegetative bacteria. The restoration of effectiveness supports our earlier conclusion that the mutation is not in the structural gene for a suggested common subunit of nitrogenase and nitrate reductase.

Effect of Low Nitrate Supply on Nitrogen Fixation in Alfalfa Root Nodules Induced by Rhizobium meliloti Strains with Varied Nitrate Reductase Activity

1989 ◽  
Vol 135 (2) ◽  
pp. 207-211 ◽  
Author(s):  
Cesáreo Arrese-Igor ◽  
José M. Estavillo ◽  
José I. Peña ◽  
Carmen Gonzalez-Murua ◽  
Pedro M. Aparicio-Tejo
Keyword(s):  
Nitrogen Fixation ◽  
Nitrate Reductase ◽  
Nitrate Reductase Activity ◽  
Rhizobium Meliloti ◽  
Reductase Activity ◽  
Root Nodules ◽  
Nitrate Supply ◽  
Alfalfa Root

scholarly journals ABSENCE OF A CORRELATION BETWEEN NITRATE REDUCTASE AND SYMBIOTIC NITROGEN FIXATION EFFICIENCY IN RHIZOBIUM MELILOTI

1980 ◽  
Vol 60 (1) ◽  
pp. 209-212 ◽  
Author(s):  
H. ANTOUN ◽  
L. M. BORDELEAU ◽  
D. PRÉVOST ◽  
R. A. LACHANCE
Keyword(s):  
Nitrogen Fixation ◽  
Nitrate Reductase ◽  
Dry Matter ◽  
Symbiotic Nitrogen Fixation ◽  
Rhizobium Meliloti ◽  
Specific Activities ◽  
Selection Of

Specific activities of the assimilatory and "regulatory" types of nitrate reductase were studied in 41 strains of Rhizobium meliloti having different symbiotic nitrogen fixation activities. Both nitrate reductase enzymes were present in very effective and ineffective strains and no significant correlation was found between the specific activities of the two enzymes and the dry matter yields of alfalfa obtained with the 41 strains. Measurements of the specific activities of the two nitrate reductase enzymes in the vegetative bacteria cannot be used as a rapid physiological test for the selection of very effective strains of R. meliloti.

Nitrate modification of photosynthesis and photoassimilate export in young nodulated soybean plants

1982 ◽  
Vol 60 (12) ◽  
pp. 2665-2670 ◽  
Author(s):  
D. J. Ursino ◽  
D. M. Hunter ◽  
R. D. Laing ◽  
J. L. S. Keighley
Keyword(s):  
Nitrogen Fixation ◽  
Nitrate Reductase ◽  
Nutrient Solution ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Nodule Development ◽  
Nitrate Availability ◽  
Data Support ◽  
Nutrient Fertilization ◽  
Soybean Plants

Soybean plants (cv. Harosoy 63) inoculated with rhizobia were germinated from seed and beginning on day 7 after planting were subjected to one of four patterns of nutrient fertilization. One group received a nutrient solution containing 5 mM nitrate, a second group received nitrate-free nutrient solution, and two other groups received nitrate-containing solution either from days 7 to 13 or from days 14 to 20. On day 21 rates of leaf photosynthetic CO2 uptake and nitrate reductase activity were measured, as well as the capacities of the leaf to export recent photosynthate and of the nodules to reduce acetylene. The data support the hypothesis that sufficient nitrate availability in the leaves of young soybean plants can modify both photosynthetic CO2 uptake and light-mediated photoassimilate export to an extent that nodule development and the capacity for nitrogen fixation are reduced.

scholarly journals MtMOT1.2 is responsible for molybdate supply toMedicago truncatulanodules

2018 ◽  
Author(s):  
Patricia Gil-Díez ◽  
Manuel Tejada-Jiménez ◽  
Javier León-Mediavilla ◽  
Jiangqi Wen ◽  
Kirankumar S. Mysore ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Symbiotic Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
Reductase Activity ◽  
Root Nodules ◽  
Loss Of Function ◽  
Intracellular Membrane ◽  
Wild Type ◽  
Endodermal Cells ◽  
Iron Molybdenum Cofactor

ABSTRACTSymbiotic nitrogen fixation in legume root nodules requires a steady supply of molybdenum for synthesis of the iron-molybdenum cofactor of nitrogenase. This nutrient has to be provided by the host plant from the soil, crossing several symplastically disconnected compartments through molybdate transporters, including members of the MOT1 family. MtMOT1.2 is aMedicago truncatulaMOT1 family member located in the endodermal cells in roots and nodules. Immunolocalization of a tagged MtMOT1.2 indicates that it is associated to the plasma membrane and to intracellular membrane systems, where it would be transporting molybdate towards the cytosol, as indicated in yeast transport assays. A loss-of-functionmot1.2-1mutant showed reduced growth compared to wild-type plants when nitrogen fixation was required, but not when nitrogen was provided as nitrate. While no effect on molybdenum-dependent nitrate reductase activity was observed, nitrogenase activity was severely affected, explaining the observed difference of growth depending on nitrogen source. This phenotype was the result of molybdate not reaching the nitrogen-fixing nodules, since genetic complementation with a wild-typeMtMOT1.2gene or molybdate-fortification of the nutrient solution, both restored wild-type levels of growth and nitrogenase activity. These results support a model in which MtMOT1.2 would mediate molybdate delivery by the vasculature into the nodules.

Nitrate reductase activities of rhizobia and the correlation between nitrate reduction and nitrogen fixation

1979 ◽  
Vol 25 (10) ◽  
pp. 1169-1174 ◽  
Author(s):  
James R. Manhart ◽  
Peter P. Wong
Keyword(s):  
Nitrogen Fixation ◽  
Nitrate Reductase ◽  
Nitrate Reduction ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Root Nodules ◽  
Sole Source ◽  
Rhizobium Japonicum ◽  
Rhizobium Trifolii ◽  
Rhizobium Species

All species of Rhizobium except R. lupini had nitrate reductase activity. Only R. lupini was incapable of growth with nitrate as the sole source of nitrogen. However, the conditions necessary for the induction of nitrate reductase varied among species of Rhizobium. Rhizobium japonicum and some Rhizobium species of the cowpea strains expressed nitrate reductase activities both in the root nodules of appropriate leguminous hosts and when grown in the presence of nitrate. Rhizobium trifolii, R. phaseoli, and R. legnminosarum did not express nitrate reductase activities in the root nodules, but they did express them when grown in the presence of nitrate. In bacteroids of R. japonicum and some strains of cowpea Rhizobium, high N2 fixation activities were accompanied by high nitrate reductase activities. In bacteroids of R. trifolii, R. leguminosarum, and R. phaseoli, high N2 fixation activities were not accompanied by high nitrate reductase activities.

Physiological indicators of nitrogen response in a short rotation sycamore plantation. II. Nitrogen metabolism

1993 ◽  
Vol 71 (6) ◽  
pp. 841-847 ◽  
Author(s):  
Timothy J. Tschaplinski ◽  
Richard J. Norby
Keyword(s):  
Amino Acids ◽  
Growth Rate ◽  
Nitrate Reductase ◽  
Nitrogen Fertilization ◽  
Free Amino ◽  
Nitrate Reductase Activity ◽  
Growth Response ◽  
Reductase Activity ◽  
Growing Season ◽  
Relative Growth

American sycamore (Platanus occidentalis L.) seedlings were grown in the field under different urea–nitrogen fertilization regimes to identify nitrogen variables that characterize the growth response. Treatments included fertilization with 50, 150, and 450 kg N/ha, periodic fertilization (three times during the growing season) at 37.5 kg N/ha, and an unfertilized control. Leaf total nitrogen concentration was a poor indicator of plant growth response to nitrogen fertilization. Salt-extractable protein, nitrate, and free amino acid concentrations all trended upward by the end of the growing season as relative growth rate declined, but treatment differences were minimal. Leaf nitrate reductase activity was consistently higher in fertilized trees before substantial leaf senescence had occurred. When leaf loss was evident, all treatments had high levels of nitrate reductase activity. Aspartic acid and glutamic acid were the most prevalent free amino acids in leaves, whereas concentrations of amine-rich amino acids were low. Although several nitrogen variables, including foliar asparagine and glycine concentrations, were positively correlated with relative growth rate (r ≥ 0.7), no single variable closely reflected treatment differences in growth response. Key words: amino acids, nitrogen, nitrate reductase, sycamore.

Further Studies on the Induction of Nitrate Reductase by Arginine in the Filamentous Cyanobacterium Oscillatoria chalybea

1992 ◽  
Vol 47 (7-8) ◽  
pp. 540-544 ◽  
Author(s):  
J. Bednarz ◽  
G. H. Schmid
Keyword(s):  
Nitrogen Fixation ◽  
Nitrate Reductase ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Filamentous Cyanobacterium ◽  
Nitrogen Fixation Activity ◽  
Fixation Activity ◽  
Cyanobacterium Anabaena ◽  
Oscillatoria Chalybea ◽  
Anabaena Pcc7120

In an earlier publication we reported on the role of arginine for the development of nitrate reductase activity in cells of the filamentous cyanobacterium Oscillatoria chalybea (Bednarz and Schmid, Z. Naturforsch. 46c, 591 (1991)). In the present paper we present further evidence that arginine is the natural inducer for nitrate reductase activity. Thus, we show that the induction is regulated by transcription, probably related to the apoprotein or the molybdenumcofactor. We also examined the influence of arginine on nitrate reductase activity in the filamentous cyanobacterium Anabaena PCC7120. In contrast to Oscillatoria chalybea this cyanobacterium forms heterocysts and shows nitrogen fixation activity. Like in Oscillatoria chalybea nitrate reductase activity in Anabaena PCC7120 is stimulated in the presence of arginine as the sole nitrogen source. However, this stimulation is limited to an early growth stage. Subsequently, nitrogen fixation activity appears and nitrate reductase activity decreases.

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