Enhanced maize productivity by inoculation with diazotrophic bacteria

2001 ◽  
Vol 28 (9) ◽  
pp. 829 ◽  
Author(s):  
Patrick J. Riggs ◽  
Marisa K. Chelius ◽  
A. Leonardo Iniguez ◽  
Shawn M. Kaeppler ◽  
Eric W. Triplett
Keyword(s):  
Nitrogen Fixation ◽  
Klebsiella Pneumoniae ◽  
International Symposium ◽  
Field Experiments ◽  
Bacterial Endophytes ◽  
Gluconacetobacter Diazotrophicus ◽  
Diazotrophic Bacteria ◽  
Fixed Nitrogen ◽  
Maize Productivity ◽  
Significant Yield

This paper originates from an address at the 8th International Symposium on Nitrogen Fixation with Non-Legumes, Sydney, NSW, December 2000 The objective of this work over the last 3 years was to identify maize–endophyte associations with increased plant productivity compared with uninoculated controls. We have used a collection of endophytes isolated by several groups. The experiments were done under field and greenhouse conditions in the presence or absence of added fixed nitrogen (N). Significant yield enhancements of N-fertilized maize were obtained with bacterial endophytes that we have isolated from N-efficient lines of maize (such as Klebsiella pneumoniae 342) or switchgrass (Pantoea agglomerans P101 and P102). Several other strains from other groups were also tested with our best yield enhancements from two Brazilian strains, Gluconacetobacter diazotrophicus PAl5 andHerbaspirillum seropedicae Z152. Field experiments in Wisconsin were conducted in 1998, 1999 and 2000 and in an additional four states (Illinois, Iowa, Indiana and Nebraska) in 2000, with a minimum of two elite lines of maize at each site, each year. No strains were capable of relieving the N-deficiency symptoms of unfertilized maize in either the field or the greenhouse.

Does the routine heat treatment of sugarcane stem pieces for xylem pathogen control affect the nitrogenase activity of an N2-fixing endophyte in the cane?

2001 ◽  
Vol 28 (9) ◽  
pp. 907 ◽  
Author(s):  
Eduardo Ortega ◽  
Rosa Rodés ◽  
Enrique de la Fuente ◽  
Loiret Fernández
Keyword(s):  
Heat Treatment ◽  
Nitrogen Fixation ◽  
International Symposium ◽  
Nitrogenase Activity ◽  
Leaf Nitrogen ◽  
Leaf Nitrogen Content ◽  
Gluconacetobacter Diazotrophicus ◽  
Pathogen Control ◽  
Sugarcane Stem ◽  
Poor Soil

This paper originates from an address at the 8th International Symposium on Nitrogen Fixation with Non-Legumes, Sydney, NSW, December 2000 In sugarcane propagation the sett pieces are routinely heated at 50˚C before planting to control the xylem pathogen Leifsonia xyli ssp. xyli. To determine whether this treatment also affects the diazotrophic endophyte, Gluconacetobacter diazotrophicus, found in the intercellular solution of cane parenchyma, cultures of this bacterium were similarly heated. The nitrogenase activity of the heated cultures was monitored by measurement of hydrogen evolution. Activity was destroyed in cultures heated directly at 45 or 50˚C for 2 h. In contrast, when sett pieces were first heated for 2 h at 50˚C, G. diazotrophicus could still be isolated from the intercellular fluid, and these cultures showed considerable nitrogenase activity. There was no difference in leaf nitrogen content of plants grown in nitrogen-poor soil from setts either heated or unheated. It is concluded that the routine heat treatment of sugarcane setts for pathogen control does not totally destroy the nitrogenase activity of the diazotrophic endophyte G. diazotrophicus.

scholarly journals Importance of cis Determinants and Nitrogenase Activity in Regulated Stability of the Klebsiella pneumoniae Nitrogenase Structural Gene mRNA

1999 ◽  
Vol 181 (12) ◽  
pp. 3751-3760 ◽  
Author(s):  
Holly M. Simon ◽  
Mark M. Gosink ◽  
Gary P. Roberts
Keyword(s):  
Nitrogen Fixation ◽  
Simple Model ◽  
Klebsiella Pneumoniae ◽  
Mrna Stability ◽  
Nitrogenase Activity ◽  
Expression System ◽  
Fixed Nitrogen ◽  
Complicated Model ◽  
A Site ◽  
Gene Mrna

ABSTRACT The Klebsiella pneumoniae nitrogen fixation (nif) mRNAs are unusually stable, with half-lives of 20 to 30 min under conditions favorable to nitrogen fixation (limiting nitrogen, anaerobiosis, temperatures of 30°C). Addition of O2 or fixed nitrogen or temperature increases to 37°C or more result in the dramatic destabilization of the nifmRNAs, decreasing the half-lives by a factor of 3 to 5. A plasmid expression system, independent of nif transcriptional regulation, was used to define cis determinants required for the regulated stability of the 5.2-kb nifHDKTY mRNA and to test the model suggested by earlier work that NifA is required in trans to stabilize nif mRNA undernif-derepressing conditions. O2 regulation ofnifHDKTY mRNA stability is impaired in a plasmid containing a deletion of a 499-bp region of nifH, indicating that a site(s) required for the O2-regulated stability of the mRNA is located within this region. The simple model suggested from earlier work that NifA is required for stabilizingnif mRNA under conditions favorable for nitrogen fixation was disproved, and in its place, a more complicated model involving the sensing of nitrogenase activity as a component of the system regulating mRNA stability is proposed. Analysis ofnifY mutants and overexpression suggests a possible involvement of the protein in this sensing process.

scholarly journals Manipulating nitrogen regulation in diazotrophic bacteria for agronomic benefit

2019 ◽  
Vol 47 (2) ◽  
pp. 603-614 ◽  
Author(s):  
Marcelo Bueno Batista ◽  
Ray Dixon
Keyword(s):  
Nitrogen Fixation ◽  
Genetic Manipulation ◽  
Current Knowledge ◽  
Ammonia Excretion ◽  
Ammonium Assimilation ◽  
Regulatory Mechanisms ◽  
Diazotrophic Bacteria ◽  
Fixed Nitrogen ◽  
Regulatory Circuits ◽  
Biological Nitrogen

AbstractBiological nitrogen fixation (BNF) is controlled by intricate regulatory mechanisms to ensure that fixed nitrogen is readily assimilated into biomass and not released to the environment. Understanding the complex regulatory circuits that couple nitrogen fixation to ammonium assimilation is a prerequisite for engineering diazotrophic strains that can potentially supply fixed nitrogen to non-legume crops. In this review, we explore how the current knowledge of nitrogen metabolism and BNF regulation may allow strategies for genetic manipulation of diazotrophs for ammonia excretion and provide a contribution towards solving the nitrogen crisis.

scholarly journals Effect of Sowing Depth on Nodulation, Nitrogen Fixation, Root and Hypocotyl Growth, and Yield in Groundnut (Arachis hypogaea)

1987 ◽  
Vol 23 (3) ◽  
pp. 283-291 ◽  
Author(s):  
P. T. C. Nambiar ◽  
B. Srinivasa Rao
Keyword(s):  
Nitrogen Fixation ◽  
Plant Growth ◽  
Field Experiments ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Growth And Yield ◽  
Fixed Nitrogen ◽  
Hypocotyl Growth ◽  
Hypocotyl Length ◽  
Sowing Depth

SUMMARYHypocotyl length in groundnut is a function of sowing depth. In field experiments deep sowing increased the mass of hypocotyl but decreased that of roots, pods and haulm. Few nodules were formed on the hypocotyls of plants from shallow sown seeds (4–5 cm deep). More hypocotyl nodules occurred on Virginia types when deep sown but the number and activity of nodules on the roots decreased. Nodules on the hypocotyl appeared later and fixed less nitrogen than root nodules. Although hypocotyl nodules fixed nitrogen during the later stages of plant growth, this activity could not compensate for the loss in nitrogenase activity due to deeper sowing. Deeper sowing also resulted in decreased pod yields.

scholarly journals Symbiotic Autoregulation of nifA Expression in Rhizobium leguminosarum bv. viciae

2004 ◽  
Vol 186 (19) ◽  
pp. 6586-6594 ◽  
Author(s):  
Marta Martínez ◽  
José M. Palacios ◽  
Juan Imperial ◽  
Tomás Ruiz-Argüeso
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Nitrogen Fixation ◽  
Klebsiella Pneumoniae ◽  
Transcription Initiation ◽  
Promoter Activity ◽  
Rhizobium Leguminosarum ◽  
Initiation Site ◽  
Diazotrophic Bacteria ◽  
Low Levels

ABSTRACT NifA is the general transcriptional activator of nitrogen fixation genes in diazotrophic bacteria. In Rhizobium leguminosarum bv. viciae UPM791, the nifA gene is part of a gene cluster (orf71 orf79 fixW orf5 fixABCX nifAB) separated by 896 bp from an upstream and divergent truncated duplication of nifH (ΔnifH). Symbiotic expression analysis of genomic nifA::lacZ fusions revealed that in strain UPM791 nifA is expressed mainly from a σ54-dependent promoter (P nifA1 ) located upstream of orf71. This promoter contains canonical NifA upstream activating sequences located 91 bp from the transcription initiation site. The transcript initiated in P nifA1 spans 5.1 kb and includes nifA and nifB genes. NifA from Klebsiella pneumoniae was able to activate transcription from P nifA1 in a heterologous Escherichia coli system. In R. leguminosarum, the P nifA1 promoter is essential for effective nitrogen fixation in symbiosis with peas. In its absence, partially efficient nitrogen-fixing nodules were produced, and the corresponding bacteroids exhibited only low levels of nifA gene expression. The basal level of nifA expression resulted from a promoter activity originating upstream of the fixX-nifA intergenic region and probably from an incomplete duplication of P nifA1 located immediately upstream of fixA.

EFFECTS OF SOIL ACIDITY ON RHIZOBIA NUMBERS, NODULATION AND NITROGEN FIXATION BY ALFALFA AND RED CLOVER

1977 ◽  
Vol 57 (2) ◽  
pp. 197-203 ◽  
Author(s):  
W. A. RICE ◽  
D. C. PENNEY ◽  
M. NYBORG
Keyword(s):  
Nitrogen Fixation ◽  
Soil Ph ◽  
Soil Acidity ◽  
Field Experiments ◽  
Rhizobium Meliloti ◽  
Acid Soils ◽  
Red Clover ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Greenhouse Experiments

The effects of soil acidity on nitrogen fixation by alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) were investigated in field experiments at 28 locations, and in greenhouse experiments using soils from these locations. The pH of the soils (limed and unlimed) varied from 4.5 to 7.2. Rhizobia populations in the soil, nodulation, and relative forage yields (yield without N/yield with N) were measured in both the field and greenhouse experiments. Rhizobium meliloti numbers, nodulation scores, and relative yields of alfalfa decreased sharply as the pH of the soils decreased below 6.0. For soils with pH 6.0 or greater, there was very little effect of pH on any of the above factors for alfalfa. Soil pH in the range studied had no effect on nodulation scores and relative yields of red clover. However, R. trifolii numbers were reduced when the pH of the soil was less than 4.9. These results demonstrate that hydrogen ion concentration is an important factor limiting alfalfa growth on acid soils of Alberta and northeastern British Columbia, but it is less important for red clover. This supports the continued use of measurements of soil pH, as well as plant-available Al and Mn for predicting crop response to lime.

scholarly journals Increase maize productivity and water use efficiency through application of potassium silicate under water stress

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. A. Gomaa ◽  
Essam E. Kandil ◽  
Atef A. M. Zen El-Dein ◽  
Mamdouh E. M. Abou-Donia ◽  
Hayssam M. Ali ◽  
...  
Keyword(s):  
Grain Yield ◽  
Water Use Efficiency ◽  
Water Deficit ◽  
Water Use ◽  
Field Experiments ◽  
Foliar Application ◽  
Potassium Silicate ◽  
Water Deficit Stress ◽  
Maize Productivity ◽  
Use Efficiency

AbstractIn Egypt, water shortage has become a key limiting factor for agriculture. Water-deficit stress causes different morphological, physiological, and biochemical impacts on plants. Two field experiments were carried out at Etay El-Baroud Station, El-Beheira Governorate, Agriculture Research Center (ARC), Egypt, to evaluate the effect of potassium silicate (K-silicate) of maize productivity and water use efficiency (WUE). A split-plot system in the four replications was used under three irrigation intervals during the 2017 and 2018 seasons. Whereas 10, 15, and 20 days irrigation intervals were allocated in main plots, while the three foliar application treatments of K-silicate (one spray at 40 days after sowing; two sprays at 40 and 60 days; and three sprays at 40, 60, and 80 days, and a control (water spray) were distributed in the subplots. All the treatments were distributed in 4 replicates. The results indicated that irrigation every 15 days gave the highest yield in both components and quality. The highly significant of (WUE) under irrigation every 20 days. Foliar spraying of K-silicate three times resulted in the highest yield. Even under water-deficit stress, irrigation every fifteen days combined with foliar application of K-silicate three times achieved the highest values of grain yield and its components. These results show that K-silicate treatment can increase WUE and produce high grain yield requiring less irrigation.

Nitrogen fixation by cell-free extracts of Klebsiella pneumoniae

1968 ◽  
Vol 14 (1) ◽  
pp. 33-38 ◽  
Author(s):  
M. C. Mahl ◽  
P. W. Wilson
Keyword(s):  
Nitrogen Fixation ◽  
Klebsiella Pneumoniae ◽  
Azotobacter Vinelandii ◽  
Ammonium Ion ◽  
Michaelis Constant ◽  
Nitrogen Gas ◽  
Aerobacter Aerogenes ◽  
Free System ◽  
Evolving System ◽  
A Cell

A cell-free system which permits nitrogen fixation by extracts of Klebsiella pneumoniae M5al (formerly Aerobacter aerogenes) has been developed. It is, essentially, that system described by Bulen and associates for Azotobacter vinelandii, utilizing ATP as a source of energy and dithionite as a source of electrons. The Michaelis constant for fixation has been estimated to be 0.12 atm. The extracts possessed an ATP-dependent hydrogen evolving system. Hydrogen evolution from these extracts was less under nitrogen than under helium in the presence of ATP. Nitrogen gas appears to be the inducer of nitrogen fixation. In the absence of N2, no induction of nitrogenase occurs. Nitrogenase is absent in cells grown on NH4+-N. There is a lag of about 13 h after the introduction of N2 gas into a culture which has depleted its supply of NH4+-N before nitrogenase can be detected. For reasons discussed in the text, this conclusion must be regarded as tentative at this time. Ammonium ion appears to prevent the synthesis of new molecules of nitrogenase without affecting the activity of those already formed.

A Synthesis of Knowns, Unknowns, and Policy Recommendations from the Sea Lamprey International Symposium

1980 ◽  
Vol 37 (11) ◽  
pp. 2202-2208 ◽  
Author(s):  
Carl J. Walters ◽  
George Spangler ◽  
W. J. Christie ◽  
Patrick J. Manion ◽  
James F. Kitchell
Keyword(s):  
International Symposium ◽  
Large Scale ◽  
Fishery Management ◽  
Field Experiments ◽  
Lake Trout ◽  
Sea Lamprey ◽  
Future Research ◽  
Fish Stock ◽  
Total Production ◽  
Pilot Studies

The Sea Lamprey International Symposium (SLIS) has provided a broad spectrum of facts and speculations for consideration in future research and management programs. Many aspects of the laboratory biology and field life history of the sea lamprey (Petromyzon marinus) are now well understood. There is little question that it can now be controlled by chemical larvicides, and perhaps in the future by more efficient integrated control programs. There is correlative evidence (wounds, scars, catch curves) that lamprey caused major mortalities in some fish species, and that control in conjunction with stocking has lead to remarkable recoveries of salmonid stocks in the Great Lakes. However, there are great gaps in understanding about just what the lamprey does under field conditions, and it is not yet possible to reject several hypotheses that assign lamprey a minimum or transient role in fish stock changes. Further studies on details of lamprey biology are, in themselves, unlikely to fill the gaps; one alternative is to conduct a large-scale field experiment involving cessation of lamprey control while holding other factors (fishing, stocking) as steady as possible. If it is decided to proceed with management on the assumption that lamprey are important, without the major field experiments to confirm it, then at least the following steps should be taken: (1) the chemical treatment program should be reviewed in detail, with a view to finding treatment schedules that will minimize frequency and dose rates for lampricide applications; (2) pilot studies on alternative control schemes (sterile male, attractants, barriers) should only be funded if they are statistically well designed (several replicate and control streams), and involve quantitative monitoring of lamprey spawning success and subsequent total production of transforming larvae; (3) the lake trout (Salvelinus namaycush) stocking program should be maintained at its present level, and should involve diverse genotypes rather than a few hatchery strains; (4) growth in the sport fisheries for lake trout should be curtailed, and commercial fisheries should not yet be permitted; (5) a multispecies harvesting policy should be designed that takes into account the buffering effect of each species on lamprey mortality suffered by others (i.e. should some species not be harvested at all, and viewed instead as buffers for more valuable species?); and (6) a program should be developed for restoring, by culture if necessary, native forage species in case the introduced smelt and alewife should collapse under pressure from fishing and prédation by the growing salmonid community.Key words: sea lamprey, proposed research, fishery management, mathematical models, population dynamics

The flavin transferase ApbE flavinylates the ferredoxin:NAD+-oxidoreductase Rnf required for N2 fixation in Azotobacter vinelandii

2021 ◽  
Author(s):  
Yulia V Bertsova ◽  
Marina V Serebryakova ◽  
Alexander A Baykov ◽  
Alexander V Bogachev
Keyword(s):  
Nitrogen Fixation ◽  
Azotobacter Vinelandii ◽  
Growth Defect ◽  
Deficient Mutant ◽  
Fixed Nitrogen ◽  
Oxidoreductase Activity ◽  
Threonine Residue ◽  
Ferredoxin Reductase ◽  
Relative Contribution ◽  
Fixation System

Abstract Azotobacter vinelandii, the model microbe in nitrogen fixation studies, uses the ferredoxin:NAD+-oxidoreductase Rnf to regenerate ferredoxin (flavodoxin) acting as an electron donor for nitrogenase. However, the relative contribution of Rnf into nitrogenase functioning is unknown because this bacterium contains another ferredoxin reductase, FixABCX. Furthermore, Rnf is flavinylated in the cell, but the importance and pathway of this modification reaction also remain largely unknown. We have constructed A. vinelandii cells with impaired activities of FixABCX and/or putative flavin transferase ApbE. The ApbE-deficient mutant could not produce covalently flavinylated membrane proteins and demonstrated a markedly decreased flavodoxin:NAD+ oxidoreductase activity and significant growth defect under diazotrophic conditions. The double ΔFix/ΔApbE mutation abolished the flavodoxin:NAD+ oxidoreductase activity and the ability of A. vinelandii to grow in the absence of fixed nitrogen source. ApbE flavinylated a truncated RnfG subunit of Rnf1 by forming a phosphoester bond between FMN and a threonine residue. These findings indicate that Rnf (presumably its Rnf1 form) is the major ferredoxin-reducing enzyme in the nitrogen fixation system and that the activity of Rnf depends on its covalent flavinylation by the flavin transferase ApbE.

Sign in / Sign up

Export Citation Format

Share Document