scholarly journals Biotechnological approaches to develop nitrogen-fixing cereals: A review

2021 ◽  
Vol 19 (4) ◽  
pp. e08R01-e08R01
Author(s):  
Asma Boujenna ◽  
Keyword(s):  
Cereal Crops ◽  
N Fixation ◽  
N Availability ◽  
Gaseous Nitrogen ◽  
Environmental Consequences ◽  
Industrialized Nations ◽  
Oxygen Sensitive ◽  
Legume Symbiosis ◽  
Living Organisms ◽  
Biological Nitrogen

ricultural yields are often limited by nitrogen (N) availability, especially in countries of the developing world, whereas in industrialized nations the application of chemical N fertilizers has reached unsustainable levels that have resulted in severe environmental consequences. Finding alternatives to inorganic fertilizers is critical for sustainable and secure food production. Although gaseous nitrogen (N2) is abundant in the atmosphere, it cannot be assimilated by most living organisms. Only a selected group of microorganisms termed diazotrophs, have evolved the ability to reduce N2 to generate NH3 in a process known as biological nitrogen fixation (BNF) catalysed by nitrogenase, an oxygen-sensitive enzyme complex. This ability presents an opportunity to improve the nutrition of crop plants, through the introduction into cereal crops of either the N fixing bacteria or the nitrogenase enzyme responsible for N fixation. This review explores three potential approaches to obtain N-fixing cereals: (a) engineering the nitrogenase enzyme to function in plant cells; (b) engineering the legume symbiosis into cereals; and (c) engineering cereals with the capability to associate with N-fixing bacteria.

scholarly journals Biotechnological approaches to develop nitrogen-fixing cereals: A review

2021 ◽  
Vol 19 (4) ◽  
pp. e08R01-e08R01
Author(s):  
Asma Boujenna ◽  
Keyword(s):  
Cereal Crops ◽  
N Fixation ◽  
N Availability ◽  
Environmental Consequences ◽  
Industrialized Nations ◽  
Oxygen Sensitive ◽  
Legume Symbiosis ◽  
Living Organisms ◽  
Agricultural Yields ◽  
Biological Nitrogen

Agricultural yields are often limited by nitrogen (N) availability, especially in countries of the developing world, whereas in industrialized nations the application of chemical N fertilizers has reached unsustainable levels that have resulted in severe environmental consequences. Finding alternatives to inorganic fertilizers is critical for sustainable and secure food production. Although gaseous nitrogen (N2) is abundant in the atmosphere, it cannot be assimilated by most living organisms. Only a selected group of microorganisms termed diazotrophs, have evolved the ability to reduce N2 to generate NH3 in a process known as biological nitrogen fixation (BNF) catalysed by nitrogenase, an oxygen-sensitive enzyme complex. This ability presents an opportunity to improve the nutrition of crop plants, through the introduction into cereal crops of either the N fixing bacteria or the nitrogenase enzyme responsible for N fixation. This review explores three potential approaches to obtain N-fixing cereals: (a) engineering the nitrogenase enzyme to function in plant cells; (b) engineering the legume symbiosis into cereals; and (c) engineering cereals with the capability to associate with N-fixing bacteria.

scholarly journals Upper Midwest lakes are supersaturated with N2

2020 ◽  
Vol 117 (29) ◽  
pp. 17063-17067 ◽  
Author(s):  
Brianna M. Loeks-Johnson ◽  
James B. Cotner
Keyword(s):  
Trophic Status ◽  
N Cycling ◽  
N Fixation ◽  
Upper Midwest ◽  
Gaseous Nitrogen ◽  
Inorganic N ◽  
N Limitation ◽  
Large Size ◽  
Traditional Paradigm ◽  
Biological Nitrogen

Little is known about the exchange of gaseous nitrogen (N2) with the atmosphere in freshwater systems. Although the exchange of N2, driven by excess or deficiencies relative to saturation values, has little relevance to the atmospheric N2pool due to its large size, it does play an important role in freshwater and marine nitrogen (N) cycling. N-fixation converts N2to ammonia, which can be used by microbes and phytoplankton, while denitrification/anammox effectively removes it by converting oxidized, inorganic N to N2. We examined N2saturation to infer net biological nitrogen processes in 34 lakes across 5° latitude varying in trophic status, mixing regime, and bathymetry. Here, we report that nearly all lakes examined in the upper Midwest (USA) were supersaturated with N2(>85% of samples,n= 248), suggesting lakes are continuously releasing nitrogen to the atmosphere. The traditional paradigm is that freshwaters compensate for N-limitation through N-fixation, but these results indicate that lakes were constantly losing N to the atmosphere via denitrification and/or anammox, suggesting that terrestrial N inputs are needed to balance the internal N cycle.

scholarly journals Insights into mechanisms governing forest carbon response to nitrogen deposition: a model–data comparison using observed responses to nitrogen addition

2013 ◽  
Vol 10 (6) ◽  
pp. 3869-3887 ◽  
Author(s):  
R. Q. Thomas ◽  
G. B. Bonan ◽  
C. L. Goodale
Keyword(s):  
Plant Uptake ◽  
Temperate Forest ◽  
Growth Response ◽  
N Fertilization ◽  
N Deposition ◽  
Forest Carbon ◽  
Biogeochemical Model ◽  
N Fixation ◽  
N Availability ◽  
Fertilization Experiments

Abstract. In many forest ecosystems, nitrogen (N) deposition enhances plant uptake of carbon dioxide, thus reducing climate warming from fossil fuel emissions. Therefore, accurately modeling how forest carbon (C) sequestration responds to N deposition is critical for understanding how future changes in N availability will influence climate. Here, we use observations of forest C response to N inputs along N deposition gradients and at five temperate forest sites with fertilization experiments to test and improve a global biogeochemical model (CLM-CN 4.0). We show that the CLM-CN plant C growth response to N deposition was smaller than observed and the modeled response to N fertilization was larger than observed. A set of modifications to the CLM-CN improved the correspondence between model predictions and observational data (1) by increasing the aboveground C storage in response to historical N deposition (1850–2004) from 14 to 34 kg C per additional kg N added through deposition and (2) by decreasing the aboveground net primary productivity response to N fertilization experiments from 91 to 57 g C m−2 yr−1. Modeled growth response to N deposition was most sensitive to altering the processes that control plant N uptake and the pathways of N loss. The response to N deposition also increased with a more closed N cycle (reduced N fixation and N gas loss) and decreased when prioritizing microbial over plant uptake of soil inorganic N. The net effect of all the modifications to the CLM-CN resulted in greater retention of N deposition and a greater role of synergy between N deposition and rising atmospheric CO2 as a mechanism governing increases in temperate forest primary production over the 20th century. Overall, testing models with both the response to gradual increases in N inputs over decades (N deposition) and N pulse additions of N over multiple years (N fertilization) allows for greater understanding of the mechanisms governing C–N coupling.

scholarly journals Symbiotic capability of calopo rhizobia from an agrisoil with different crops in Pernambuco

2013 ◽  
Vol 37 (4) ◽  
pp. 869-876 ◽  
Author(s):  
Altanys Silva Calheiros ◽  
Mario de Andrade Lira Junior ◽  
Débora Magalhães Soares ◽  
Márcia do Vale Barreto Figueiredo
Keyword(s):  
Dry Matter ◽  
Nitrogen Sources ◽  
Dry Weight ◽  
Dry Forest ◽  
Forest Zone ◽  
Symbiotic Efficiency ◽  
Total N ◽  
Calopogonium Mucunoides ◽  
Legume Symbiosis ◽  
Biological Nitrogen

Biological nitrogen fixation by rhizobium-legume symbiosis represents one of the most important nitrogen sources for plants and depends strongly on the symbiotic efficiency of the rhizobium strain. This study evaluated the symbiotic capacity of rhizobial isolates from calopo (CALOPOGONIUM MUCUNOIDES) taken from an agrisoil under BRACHIARIA DECUMBENS pasture, sabiá (MIMOSA CAESALPINIIFOLIA) plantations and Atlantic Forest areas of the Dry Forest Zone of Pernambuco. A total of 1,575 isolates were obtained from 398 groups. A single random isolate of each group was authenticated, in randomized blocks with two replications. Each plant was inoculated with 1 mL of a bacterial broth, containing an estimated population of 10(8) rhizobial cells mL-1. Forty-five days after inoculation, the plants were harvested, separated into shoots, roots and nodules, oven-dried to constant mass, and weighed. Next, the symbiotic capability was tested with 1.5 kg of an autoclaved sand:vermiculite (1:1) mixture in polyethylene bags. The treatments consisted of 122 authenticated isolates, selected based on the shoot dry matter, five uninoculated controls (treated with 0, 50, 100, 150, or 200 kg ha-1 N) and a control inoculated with SEMIA 6152 (=BR1602), a strain of BRADYRHIZOBIUM JAPONICUM The test was performed as described above. The shoot dry matter of the plants inoculated with the most effective isolates did not differ from that of plants treated with 150 kg ha-1 N. Shoot dry matter was positively correlated with all other variables. The proportion of effective isolates was highest among isolates from SABIÁ forests. There was great variation in nodule dry weight, as well as in N contents and total N.

scholarly journals Recent Advances in Biological Nitrogen Fixation

Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1941
Author(s):  
Jerzy Wielbo
Keyword(s):  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Recent Advances ◽  
Living Organisms ◽  
Biological Nitrogen

Nitrogen is essential for the growth and functioning of all living organisms; however, only 2% of Earth’s nitrogen is available for them [...]

Effects of balsam poplar (Populus balsamifera) tannins and low molecular weight phenolics on microbial activity in taiga floodplain soil: implications for changes in N cycling during succession

1996 ◽  
Vol 74 (1) ◽  
pp. 84-90 ◽  
Author(s):  
Joshua P. Schimel ◽  
Keith Van Cleve ◽  
Rex G. Cates ◽  
Thomas P. Clausen ◽  
Paul B. Reichardt
Keyword(s):  
Molecular Weight ◽  
Secondary Compounds ◽  
N Cycling ◽  
Low Molecular Weight ◽  
N Fixation ◽  
N Availability ◽  
Populus Balsamifera ◽  
Floodplain Soil ◽  
Balsam Poplar ◽  
River Floodplains

The transition from alder (Alnus tenuifolia) to balsam poplar (Populus balsamifera) is a critical turning point in primary succession on river floodplains in interior Alaska. Associated with the change in plant species are large changes in N cycling. N-fixation and nitrification decrease and the system becomes N-limited, with NH4+ dominating the inorganic N pool. Balsam poplar leaves contain large quantities of tannins and low molecular weight phenolic compounds. We evaluated the effect of these compounds on microbial respiration and N cycling in laboratory assays on soils from an alder-dominated site. Plant compounds were purified and applied to silica gel as an inert carrier. Both tannins and phenolics caused net N-immobilization over a 30-day assay. However, tannins inhibited respiration while phenolics stimulated it. There were no specific effects on nitrification. Thus, tannins acted as a general microbial inhibitor, while phenolics acted as a growth substrate. By inhibiting mineralization while stimulating immobilization, poplar secondary compounds may reduce soil N-availability during the transition betwen alder and poplar stages in succession. Keywords: respiration, mineralization, tannins, secondary chemicals, succession, plant–microbe interactions.

Exploring the alternatives of biological nitrogen fixation

Metallomics ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 523-538 ◽  
Author(s):  
Florence Mus ◽  
Alexander B. Alleman ◽  
Natasha Pence ◽  
Lance C. Seefeldt ◽  
John W. Peters
Keyword(s):  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Oxygen Sensitive ◽  
Biological Nitrogen

Most biological nitrogen fixation (BNF) results from the activity of the molybdenum nitrogenase (Mo-nitrogenase, Nif), an oxygen-sensitive metalloenzyme complex found in all known diazotrophs.

scholarly journals Insights into mechanisms governing forest carbon response to nitrogen deposition: a model-data comparison using observed responses to nitrogen addition

2013 ◽  
Vol 10 (1) ◽  
pp. 1635-1683 ◽  
Author(s):  
R. Q. Thomas ◽  
G. B. Bonan ◽  
C. L. Goodale
Keyword(s):  
Plant Uptake ◽  
Temperate Forest ◽  
Growth Response ◽  
N Fertilization ◽  
N Deposition ◽  
Forest Carbon ◽  
Biogeochemical Model ◽  
N Fixation ◽  
N Availability ◽  
Fertilization Experiments

Abstract. In many forest ecosystems, nitrogen (N) deposition enhances plant uptake of carbon dioxide, thus reducing climate warming from fossil fuel emissions. Therefore, accurately modeling how forest carbon (C) sequestration responds to N deposition is critical for understanding how future changes in N availability will influence climate. Here, we use observations of forest C response to N inputs along N deposition gradients and at five temperate forest sites with fertilization experiments to test and improve a~global biogeochemical model (CLM-CN 4.0). We show that the CLM-CN plant C growth response to N deposition was smaller than observed and the modeled response to N fertilization was larger than observed. A set of modifications to the CLM-CN improved the correspondence between model predictions and observational data (1) by increasing the aboveground C storage in response to historical N deposition (1850–2004) from 14 to 34 kg C per additional kg N added through deposition and (2) by decreasing the aboveground net primary productivity response to N fertilization experiments from 91 to 57 g C m−2 yr−1. Modeled growth response to N deposition was most sensitive to altering the processes that control plant N uptake and the pathways of N loss. The response to N deposition also increased with a more closed N cycle (reduced N fixation and N gas loss) and decreased when prioritizing microbial over plant uptake of soil inorganic N. The net effect of all the modifications to the CLM-CN resulted in greater retention of N deposition and a greater role of synergy between N deposition and rising atmospheric CO2 as a mechanism governing increases in temperate forest primary production over the 20th century. Overall, testing models with both the response to gradual increases in N inputs over decades (N deposition) and N pulse additions of N over multiple years (N fertilization) allows for greater understanding of the mechanisms governing C-N coupling.

scholarly journals Revisiting Biological Nitrogen Fixation Dynamics in Soybeans

2021 ◽  
Vol 12 ◽  
Author(s):  
Ignacio A. Ciampitti ◽  
André Froes de Borja Reis ◽  
S. Carolina Córdova ◽  
Michael J. Castellano ◽  
Sotirios V. Archontoulis ◽  
...  
Keyword(s):  
Maximum Rate ◽  
Seasonal Pattern ◽  
Single Point ◽  
Clay Content ◽  
Growth Stages ◽  
N Fixation ◽  
N Budget ◽  
Fixation Rate ◽  
N Removal ◽  
Biological Nitrogen

Biological nitrogen (N) fixation is the most relevant process in soybeans (Glycine max L.) to satisfy plant N demand and sustain seed protein formation. Past studies describing N fixation for field-grown soybeans mainly focused on a single point time measurement (mainly toward the end of the season) and on the partial N budget (fixed-N minus seed N removal), overlooking the seasonal pattern of this process. Therefore, this study synthesized field datasets involving multiple temporal measurements during the crop growing season to characterize N fixation dynamics using both fixed-N (kg ha−1) and N derived from the atmosphere [Ndfa (%)] to define: (i) time to the maximum rate of N fixation (β2), (ii) time to the maximum Ndfa (α2), and (iii) the cumulative fixed-N. The main outcomes of this study are that (1) the maximum rate of N fixation was around the beginning of pod formation (R3 stage), (2) time to the maximum Ndfa (%) was after full pod formation (R4), and (3) cumulative fixation was positively associated with the seasonal vapor-pressure deficit (VPD) and growth cycle length but negatively associated with soil clay content, and (4) time to the maximum N fixation rate (β2) was positively impacted by season length and negatively impacted by high temperatures during vegetative growth (but positively for VPD, during the same period). Overall, variation in the timing of the maximum rate of N fixation occurred within a much narrower range of growth stages (R3) than the timing of the maximum Ndfa (%), which varied broadly from flowering (R1) to seed filing (R5–R6) depending on the evaluated studies. From a phenotyping standpoint, N fixation determinations after the R4 growth stage would most likely permit capturing both maximum fixed-N rate and maximum Ndfa (%). Further investigations that more closely screen the interplay between N fixation with soil-plant-environment factors should be pursued.

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