Studies on nitrogen fixation by antibiotic-resistant mutants ofAzospirillum brasilenseand their interaction with cheena (Panicum miliaceumL.) genotypes in calcareous soil

1985 ◽  
Vol 105 (2) ◽  
pp. 261-270 ◽  
Author(s):  
R. Rai
Keyword(s):  
Nitrogen Fixation ◽  
Calcareous Soil ◽  
Nitrogenase Activity ◽  
Dry Weight ◽  
Resistant Mutant ◽  
Hydrogenase Activity ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Antibiotic Resistant ◽  
Mutant Strains

SUMMARYAzospirillum brasilense was treated with nitrosoguanidine and five antibiotic-resistant mutant strains isolated. Variations in growth, N2-fixation, ultraviolet-dark survival and level of antibiotic resistance were found between the mutant strains. Mutant strains STR 112 and KR 2051 showed maximum nitrogenase activity, glutamine synthetase activity and hydrogenase activity (H2uptake) at 32 °C and 40 °C respectively. Inoculation of cheena genotypes withA. brasilenseand its mutants led to significant increase in associative nitrogen fixation, dry weight of roots and grain yield compared with the uninoculated control, with significant strains × genotypes interactions in calcareous soil. It was also noted that under laboratory conditionsAzospirilluminoculation may have produced its response by hormonal means and/or associative N2-fixation.

Studies on associative nitrogen fixation by antibiotic-resistant mutants ofAzospirillum brasilensewith genotypes of lentil (Lens culinaris)Rhizobiumstrains in calcareous soil

1985 ◽  
Vol 104 (1) ◽  
pp. 207-215 ◽  
Author(s):  
R. Rai
Keyword(s):  
Nitrogen Fixation ◽  
Azospirillum Brasilense ◽  
Calcareous Soil ◽  
Lens Culinaris ◽  
Nitrogenase Activity ◽  
Dry Weight ◽  
Antibiotic Resistant ◽  
Uninoculated Control ◽  
Resistant Mutants ◽  
Antibiotic Resistant Mutants

SummaryNitrosoguanidine-induced mutation frequencies for resistance to streptomycin, spectinomycin, erythromycin and novomycin were studied inAzospirillum brasilense.Lentil inoculated withA. brasilenseand its mutants andRhizobiumstrains produced increased nodule dry weight, nitrogenase activity of nodules and roots and grain yield compared with an uninoculated control.

Competitiveness and effectiveness of carbendazim-resistant mutant and indigenous Rhizobiumstrains of chick pea (Cicer arietinutnLinn.) in calcareous soil

1985 ◽  
Vol 104 (2) ◽  
pp. 341-344 ◽  
Author(s):  
R. Rai
Keyword(s):  
Calcareous Soil ◽  
Nitrogenase Activity ◽  
Reductase Activity ◽  
Dry Weight ◽  
Resistant Mutant ◽  
Triphenyl Tetrazolium Chloride ◽  
Tetrazolium Chloride ◽  
Chick Pea ◽  
Active Iron ◽  
Mutant Strains

SummaryChick pea Rhizobiumstrain RG 4 was treated with 30 /tg/ml of N-nitrosoguanidine and four mutants isolated were resistant to 400 /tg carbendazim/ml. Only two of the mutants (M 1 and M 4) retained the capacity to form nodules. On the basis of number of nodules, their dry weight, nitrogenase activity, triphenyl tetrazolium chloride reductase activity and active iron content of nodules, mutant strains M 1 and M 4 were found to be equally effective for nitrogen fixation both with and without carbendazim (bavistine) and resulted in significantly greater grain yield than the corresponding uninoculated treatments.

High-temperature-adaptedAzospirillum brasilensestrains: growth and interaction response on associative nitrogen fixation, mineral uptake and yield of cheena (Panicum miliaceumL.) genotypes in calcareous soil

1988 ◽  
Vol 110 (2) ◽  
pp. 321-329 ◽  
Author(s):  
R. Rai
Keyword(s):  
Nitrogen Fixation ◽  
High Temperature ◽  
Calcareous Soil ◽  
Nitrogenase Activity ◽  
Dry Weight ◽  
Cross Resistance ◽  
Mineral Uptake ◽  
Associative Nitrogen Fixation ◽  
Seed Inoculation ◽  
Resistance To Penicillin

SummaryHigh-temperature-adapted strains RAU 1, RAU 2 and RAU 3 ofAzospirillum brasilenseC 7 were isolated from stepwise transfer to higher temperature (30 to 42 °C). One of the strains (RAU 1) showed more growth, greater nitrogenase and hydrogenase activities at 30 and 42 °C than parental and other temperature-adapted strains. This strain also showed growth and more nitrogenase activity from pH 6·5 to 8·0. Strain RAU 1 showed cross-resistance to penicillin (300/µg/ml) but not to streptomycin, kanamycin, viomycin and polymixin B at 30 and 42 °C. It was demonstrated in field plots in calcareous soil that seed inoculation with RAU 1 enhanced mineral uptake of cheena. Inoculation with RAU 1 led to a significant increase in associative nitrogen fixation, dry weight of roots, grain and straw yield of cheena compared with the uninoculated control with or without applied N, but the effect of seed inoculation with high-temperature-adapted strains was variable with different genotypes of cheena.

Phorate-resistant mutant strains of chick pea (Cicer arietinumL.)Rhizobiumsp. growth and their compatibility in symbiotic nitrogen fixation

1982 ◽  
Vol 98 (3) ◽  
pp. 547-551 ◽  
Author(s):  
R. Rai ◽  
R. B. Sinha ◽  
V. Prasad
Keyword(s):  
Nitrogen Fixation ◽  
Grain Yield ◽  
Symbiotic Nitrogen Fixation ◽  
Dry Weight ◽  
Resistant Mutant ◽  
Pyridine Nucleotides ◽  
Chick Pea ◽  
Active Iron ◽  
Mutant Strains

SUMMARYChick peaRhizobiumstrain RG3 was treated with 30 μg/ml of N-nitrosoguanidine and two mutants isolated were resistant to 2000 μg phorate/ml yet retained the capacity to form nodules. On the basis of number of nodules, their dry weight, N2ase activity, total pyridine nucleotides and active iron contents, mutant strains G11 and G26 were found to be equally effective with and without phorate and resulted in significantly greater grain yield.

Studies on compatibility of nitrogen fixation by high-temperature-adapted Rhizobium strains and Vigna radiata genotypes at two moisture levels in calcareous soil

1983 ◽  
Vol 101 (2) ◽  
pp. 377-381 ◽  
Author(s):  
R. Rai ◽  
V. Prasad
Keyword(s):  
Nitrogen Fixation ◽  
High Temperature ◽  
Grain Yield ◽  
Vigna Radiata ◽  
Calcareous Soil ◽  
Nitrogenase Activity ◽  
Summer Season ◽  
Green Gram ◽  
Rhizobium Strains

SUMMARYRhizobium strains adapted to high temperature, and genotypes of green gram, were used to study the symbiotic N2-fixation in a summer season at two moisture levels in calcareous soil. Different interactions between strains and genotypes were observedatthe two moisture levels. At both moisture levels, strain S4 with the green gram genotype S8 showed the greatest grain yield, nitrogenase activity, leghaemoglobin and ethanolsoluble carbohydrate of nodules.

Bidirectional Selection for Nitrogenase Activity and Shoot Dry Weight Among Late Generation Progenies of a Virginia x Spanish Peanut Cross1

1986 ◽  
Vol 13 (2) ◽  
pp. 86-89 ◽  
Author(s):  
S. Arrendell ◽  
J. C. Wynne ◽  
G. H. Elkan ◽  
T. J. Schneeweis
Keyword(s):  
Nitrogen Fixation ◽  
Plant Growth ◽  
Growth Habit ◽  
Nitrogenase Activity ◽  
Dry Weight ◽  
Fruit Weight ◽  
Shoot Dry Weight ◽  
Plant Growth Habit ◽  
The Mean ◽  
Selection For

Abstract Improvement of the host contribution to nitrogen fixation has been proposed as a method of increasing nitrogen fixation. Significant variability and generally high broad-sense heritability estimates (.60 ± .27 to .82 ± .26 for nitrogenase activity and .53 ± .29 to .85 ± .26 for shoot dry weight) have been reported for F2-derived families from a cross between the Virginia (Arachis hypogaea L. ssp. hypogaea var. hypogaea) cultivar NC 6 and the Spanish (ssp. fastigiata Waldron vulgaris Harz.) breeding line 922, indicating selection for increased nigtogen fixation should be effective in this population. Lines from this population were chosen randomly from F2-derived families selected for high and low nitrogenase activity and high and low shoot dry weight after evaluation at three dates and two locations in each of 2 years (F5 and F6 generations). This study's objectives were to evaluate the N2-fixing ability of the selected lines and to evaluate the association between plant growth habit and N2 fixation. Twenty-four lines in each of the four selection groups and the parents, NC 6 and 922, were evaluated at two sampling dates and two locations. Mean nitrogenase activity of lines selected for increased nitrogenase activity was significantly greater than the mean of the lines selected for low nitrogenase activity. Improved nitrogenase activity was associated with increased fruit weight. The fruit weight mean of the group selected for increased fruit weight. The fruit weight mean of the group selected for increased nitrogenase activity was 39% greater than the mean of the group selected for low nitrogenase activity. Mean shoot dry weight of lines selected for increased shoot dry weight was significantly greater than the mean of the lines selected for low shoot dry weight; however, the fruit weight means of these two groups did not differ. It was hypothesized that selection for increased N2 fixation in a population derived from a cross between Virginia and Spanish types would eliminate genotypes with Spanish growth habit. Groups selected for high nitrogenase activity and for high shoot dry weight had longer and wider leaflets, longer cotyledonary laterals and greater main stem height than did their respective low selection groups. However, these traits chosen to characterize plant growth habit were inadequate in discriminating parental growth habits. Consequently, the data neither substantiated nor refuted the hypothesis.

Effect of pyruvate on the metabolic regulation of nitrogenase activity in Rhodospirillum rubrum in darkness

Microbiology ◽  
2011 ◽  
Vol 157 (6) ◽  
pp. 1834-1840 ◽  
Author(s):  
Tiago Toscano Selao ◽  
Tomas Edgren ◽  
He Wang ◽  
Agneta Norén ◽  
Stefan Nordlund
Keyword(s):  
Nitrogen Source ◽  
Metabolic Regulation ◽  
Rhodospirillum Rubrum ◽  
De Novo ◽  
Nitrogenase Activity ◽  
Signal Transduction Pathway ◽  
Nitrogen Sources ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Fe Protein

Rhodospirillum rubrum, a photosynthetic diazotroph, is able to regulate nitrogenase activity in response to environmental factors such as ammonium ions or darkness, the so-called switch-off effect. This is due to reversible modification of the Fe-protein, one of the two components of nitrogenase. The signal transduction pathway(s) in this regulatory mechanism is not fully understood, especially not in response to darkness. We have previously shown that the switch-off response and metabolic state differ between cells grown with dinitrogen or glutamate as the nitrogen source, although both represent poor nitrogen sources. In this study we show that pyruvate affects the response to darkness in cultures grown with glutamate as nitrogen source, leading to a response similar to that in cultures grown with dinitrogen. The effects are related to PII protein uridylylation and glutamine synthetase activity. We also show that pyruvate induces de novo protein synthesis and that inhibition of pyruvate formate-lyase leads to loss of nitrogenase activity in the dark.

scholarly journals NODULE SENESCENCE AND BIOMASS COMPONENTS IN COMMON BEAN CULTIVARS

2008 ◽  
Vol 31 (3) ◽  
pp. 195
Author(s):  
Fabián Fernández-Luqueño ◽  
David Espinosa-Victoria ◽  
Antonio Munive ◽  
Langen Corlay Chee ◽  
Luis M. Serrano-Covarrubias
Keyword(s):  
Nitrogen Fixation ◽  
Common Bean ◽  
Nitrogenase Activity ◽  
Dry Weight ◽  
Type I ◽  
Fresh Weight ◽  
Symbiotic Relationships ◽  
Nodule Senescence ◽  
Biomass Components ◽  
Growth Habits

Most legumes establish mutualistic symbiotic relationships with atmospheric nitrogen-fixing bacteria (rhizobia), giving origin to nodules. Nodules exhibit natural or induced aging which coincides with the drop in nitrogenase activity at the flowering period or at the pod filling stage. In this research, the onset of nodule senescence (NS) was evaluated under greenhouse conditions in five common bean (Phaseolus vulgaris L.) cultivars of two growth habits, determined (Type I) and indeterminate (Type III), inoculated with Rhizobium etli CE-3. Weekly destructive samplings were taken to determine nitrogen fixation by the acetylene reduction assay, the number and fresh weight of nodules, as well as root and above ground biomass dry weight. It was found that NS in bean appears to be independent of host plant phenological stage (flowering or pod filling), the longer period the symbiotic system is fixing nitrogen the greater yield is obtained, and that the nodules number and fresh weight are reliable indicators of the nitrogen fixation capacity.

Interactions Between Growth, Phosphate Content and Nitrogen Fixation in Mycorrhizal and Non-Mycorrhizal Medicago sativa

1977 ◽  
Vol 4 (3) ◽  
pp. 403 ◽  
Author(s):  
SE Smith ◽  
MJ Daft
Keyword(s):  
Nitrogen Fixation ◽  
Medicago Sativa ◽  
Nitrogenase Activity ◽  
Mycorrhizal Fungus ◽  
Infection Intensity ◽  
Dry Weight ◽  
Phosphate Content ◽  
Mycorrhizal Infection ◽  
Measured Intensity ◽  
Mycorrhizal Plants

Nodulated Medicago sativa cv. Europe plants, both non-mycorrhizal and mycorrhizal (inoculated with Glomus mosseae), were grown in sand or soil with a range of phosphate levels. The following parameters were measured: intensity of mycorrhizal infection, intensity of nodulation, growth, phosphate content, nitrogenase activity (acetylene reduction) and nitrogen content. Both nodulation and mycorrhizal infection had occurred within 2 weeks of inoculation with the appropriate endophytes. Major increases in dry weight of mycorrhizal plants were not apparent until approximately 10 weeks from inoculation. However, mycorrhizal plants showed more extensive nodulation, coupled with higher rates of nitrogenase activity from 2 weeks onwards, and at the final (12-week) harvest had higher values of % N. Phosphate content of mycorrhizal plants (�g P/g dry wt) was also greater than non-mycorrhizal plants at 7 weeks. By 10 or 12 weeks, when significant mycorrhizal enhancement of growth was apparent, the total nitrogen and total phosphorus per mycorrhizal plant were also higher, but nitrogenase activity and phosphate content measured on a dry weight basis showed no significant differences between mycorrhizal and non-mycorrhizal plants. It is clear that mycorrhizal enhancement of phosphate uptake and nitrogen fixation precedes any effect on growth and the results indicate the importance of the time factor in the development of this tripartite symbiosis between legume, Rhizobium and mycorrhizal fungus.

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