Use of spermosphere model for the screening of wheat cultivars and N2-fixing bacteria for N2 fixation

1986 ◽  
Vol 32 (4) ◽  
pp. 285-288 ◽  
Author(s):  
Devender K. Jain ◽  
R. J. Rennie
Keyword(s):  
Yeast Extract ◽  
N2 Fixation ◽  
Azospirillum Brasilense ◽  
Incubation Temperature ◽  
Wheat Cultivars ◽  
Wheat Roots ◽  
Naoh Solution ◽  
Reducing Activity ◽  
Acetylene Reducing Activity ◽  
Very High

The spermosphere model showed very high seedling-to-seedling variation in the ability to induce acetylene-reducing activity in bacteria associated with wheat roots. Several seedlings failed to induce nitrogenase in N2-flxing strains of Bacillus and Azospirillum brasilense. Increasing the concentration of yeast extract or the inoculum density, adding NaOH solution in the side arm of Pankhurst tubes to absorb CO2, and vernalizing the seeds did not increase the percentage of nitrogenase-positive tubes and did not decrease variation in acetylene-reducing activity. Increasing the incubation temperature from 25 to 27 °C induced nitrogenase in Bacillus, but not in Azospirillum strains; at 30 °C nitrogenase was also induced in Azospirillum strains. It appears that the spermosphere model is not a practical technique for screening nitrogenase induction by wheat, unless the use of genetic lines of unimpeachable uniformity can provide control of variability.

Nitrogen fixation associated with grasses in Oregon

1976 ◽  
Vol 22 (4) ◽  
pp. 523-530 ◽  
Author(s):  
Arthur D. Nelson ◽  
Lynn E. Barber ◽  
John Tjepkema ◽  
Sterling A. Russell ◽  
Robert Powelson ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Aerobic Bacteria ◽  
Bacillus Species ◽  
Natural Conditions ◽  
Wheat Roots ◽  
Natural Grasslands ◽  
Reduction Assay ◽  
Reducing Activity ◽  
Acetylene Reducing Activity ◽  
Root Surfaces

Nitrogen fixation associated with both natural grasslands and grain crops of Oregon was studied using the acetylene-reduction assay. A number of the grasses collected had some acetylene-reducing activity. Agrostis tenuis Sibth. had substantially greater activity than any of the other species, with a mean rate estimated at 37 g N2 fixed per hectare per day. Assuming 100 days of activity, about 3 kg of N2 would be fixed per hectare per year. This quantity of nitrogen may be important in the maintenance of this species under natural conditions. Nitrogen-fixing microorganisms were isolated from the root surfaces of some of the grasses. Cultures of Bacillus macerans, Bacillus polymyxa, and Enterobacter cloacae were isolated from wheat roots as were two cultures which have not been assigned a specific taxonomic classification. Strains of N2-fixing Bacillus species and Gram-negative aerobic bacteria were isolated from Festuca and Agrostis.

Temperature sensitivity of nitrogen fixation in Azospirillum spp.

1992 ◽  
Vol 38 (12) ◽  
pp. 1238-1241 ◽  
Author(s):  
Anil K. Tripathi ◽  
Walter Klingmüller
Keyword(s):  
Nitrogen Fixation ◽  
Azospirillum Brasilense ◽  
Nitrogenase Activity ◽  
Lacz Fusion ◽  
Optimum Growth ◽  
Azospirillum Lipoferum ◽  
Reducing Activity ◽  
Acetylene Reducing Activity ◽  
The Impact ◽  
Key Words Temperature

Azospirillum brasilense and Azospirillum lipoferum showed optimum acetylene-reducing activity at 25 and 30 °C, respectively, although both the bacteria grew optimally at 35 °C. Azospirillum halopraeferens displayed optimum growth and acetylene-reducing activity at 40–41 °C. Our experiments indicated that expression of nif genes was generally more sensitive to temperature than was nitrogenase activity. The NifA-dependent activation of a heterologous nifH–lacZ fusion was used to assess the impact of temperature on native NifA activity of A. brasilense and A. lipoferum. Maximum NifA activity was observed at 25 °C in A. brasilense and at 30 °C in A. lipoferum. Key words: temperature, nitrogen fixation, nifH–lacZ fusion, NifA activity, Azospirillum.

scholarly journals Expression and function of the cdgD gene, encoding a CHASE–PAS-DGC-EAL domain protein, in Azospirillum brasilense

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
José Francisco Cruz-Pérez ◽  
Roxana Lara-Oueilhe ◽  
Cynthia Marcos-Jiménez ◽  
Ricardo Cuatlayotl-Olarte ◽  
María Luisa Xiqui-Vázquez ◽  
...  
Keyword(s):  
Azospirillum Brasilense ◽  
Type Strain ◽  
Wild Type Strain ◽  
Soil Conditions ◽  
Wild Type ◽  
Gene Encoding ◽  
Wheat Roots ◽  
Genes Encoding ◽  
In The Wild ◽  
Plant Growth Promoting

AbstractThe plant growth-promoting bacterium Azospirillum brasilense contains several genes encoding proteins involved in the biosynthesis and degradation of the second messenger cyclic-di-GMP, which may control key bacterial functions, such as biofilm formation and motility. Here, we analysed the function and expression of the cdgD gene, encoding a multidomain protein that includes GGDEF-EAL domains and CHASE and PAS domains. An insertional cdgD gene mutant was constructed, and analysis of biofilm and extracellular polymeric substance production, as well as the motility phenotype indicated that cdgD encoded a functional diguanylate protein. These results were correlated with a reduced overall cellular concentration of cyclic-di-GMP in the mutant over 48 h compared with that observed in the wild-type strain, which was recovered in the complemented strain. In addition, cdgD gene expression was measured in cells growing under planktonic or biofilm conditions, and differential expression was observed when KNO3 or NH4Cl was added to the minimal medium as a nitrogen source. The transcriptional fusion of the cdgD promoter with the gene encoding the autofluorescent mCherry protein indicated that the cdgD gene was expressed both under abiotic conditions and in association with wheat roots. Reduced colonization of wheat roots was observed for the mutant compared with the wild-type strain grown in the same soil conditions. The Azospirillum-plant association begins with the motility of the bacterium towards the plant rhizosphere followed by the adsorption and adherence of these bacteria to plant roots. Therefore, it is important to study the genes that contribute to this initial interaction of the bacterium with its host plant.

An improved selection technique and medium for the isolation and enumeration of Azospirillum brasilense

1985 ◽  
Vol 31 (10) ◽  
pp. 947-952 ◽  
Author(s):  
Yoav Bashan ◽  
Hanna Levanony
Keyword(s):  
Azospirillum Brasilense ◽  
Sodium Deoxycholate ◽  
Selective Medium ◽  
Most Probable Number ◽  
Streptomycin Sulphate ◽  
Triphenyltetrazolium Chloride ◽  
Wheat Roots ◽  
Semisolid Medium ◽  
Probable Number ◽  
Selection Technique

An improved selection technique for isolation and enumeration of Azospirillum brasilense was developed. The technique is based on successive liquid enrichments in nitrogen-free semisolid medium supplemented with streptomycin, followed by the most probable number counting method and verification on a selective medium. The latter is based on Okon's nitrogen-free medium supplemented with cycloheximide (250 mg/L), streptomycin sulphate (200 mg/L), sodium deoxycholate (200 mg/L), 2,3,5-triphenyltetrazolium chloride (15 mg/L), and Congo red (1000 mg/L). This medium was found to be superior to other available diagnostic media. The technique was readily applied to detect and count A. brasilense Cd in inoculated wheat roots.

scholarly journals Compatibility of Azospirillum brasilense with fungicide and insecticide and its effects on the physiological quality of wheat seeds

2018 ◽  
Vol 39 (2) ◽  
pp. 855 ◽  
Author(s):  
Janete Denardi Munareto ◽  
Thomas Newton Martin ◽  
Tania Maria Müller ◽  
Ubirajara Russi Nunes ◽  
Guilherme Bergeijer da Rosa ◽  
...  
Keyword(s):  
Azospirillum Brasilense ◽  
Seed Treatment ◽  
Accelerated Aging ◽  
Triticum Aestivum L ◽  
Wheat Cultivars ◽  
Pests And Diseases ◽  
Physiological Quality ◽  
Growth Promoting ◽  
Germination Vigor

Seed treatment is a practice that helps the initial establishment of the crop without the effects caused by pests and diseases. The association of diazotrophic bacteria with grasses has been used in the supply of nitrogen to plants; however, these microorganisms produce growth-promoting substances, which promote benefits in the growth and development of the crops. Thus, the objective of this study was to evaluate the compatibility of Azospirillum brasilense associated with the fungicide difenoconazole and the insecticide thiamethoxam by observing the effects on the quality of seed emergence of three wheat cultivars (Triticum aestivum L.). Three wheat cultivars, arranged in a 4 x 2 factorial system with four replicates, were tested. The treatments were the control; difenoconazole (Spectro® at a dose of 150 mL per 100 kg of seed); thiamethoxam (Cruiser® FS 350 at a dose of 200 mL per 100 kg seed) and difenoconazole + thiamethoxam, applied on wheat cultivars TBIO Mestre, TBIO Itaipu and TBIO Sinuelo. Bacteria from the Azospirillum genus were used in the inoculation. The wheat seed retains its quality when it checks the germination, vigor and independent accelerated aging, whether or not fungicide, insecticide and A. brasilense were used. The insecticide thiamethoxam increased the length of shoots and roots and provided compatibility with A. brasilense, and fungicide inhibited the length of shoots and roots and was antagonistic to the bacterium A. brasilense.

scholarly journals Two different modes of attachment of Azospirillum brasilense Sp7 to wheat roots

1991 ◽  
Vol 137 (9) ◽  
pp. 2241-2246 ◽  
Author(s):  
K. W. Michiels ◽  
C. L. Croes ◽  
J. Vanderleyden
Keyword(s):  
Azospirillum Brasilense ◽  
Wheat Roots ◽  
Azospirillum Brasilense Sp7

Nitrogen fixation (acetylene reduction) by Klebsiella pneumoniae in association with 'Park' Kentucky bluegrass (Poa pratensis L.)

1981 ◽  
Vol 27 (1) ◽  
pp. 52-56 ◽  
Author(s):  
L. V. Wood ◽  
R. V. Klucas ◽  
R. C. Shearman
Keyword(s):  
Nitrogen Fixation ◽  
Klebsiella Pneumoniae ◽  
Ethylene Production ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Poa Pratensis ◽  
Kentucky Bluegrass ◽  
Surface Sterilization ◽  
Reducing Activity ◽  
Acetylene Reducing Activity

Turfs of 'Park' Kentucky bluegrass reestablished in the greenhouse and inoculated with Klebsiella pneumoniae (W6) showed significantly increased nitrogen fixation (acetylene reduction) compared with control turfs. Mean ethylene production rates per pot were 368 nmol h−1 for K. pneumoniae treated turfs, 55 nmol h−1 for heat-killed K. pneumoniae treated turfs, and 44 nmol h−1 for untreated turfs. Calculated lag periods before activity was observed were generally very short (less than 1 h).When 'Park' Kentucky bluegrass was grown from seed on soil-less medium of Turface, a fired aggregate clay, inoculation with K. pneumoniae (W6) resulted in 9 of 11 turfs showing nitrogenase activity (mean ethylene producion rate per pot was 195 nmol h−1). Only 3 of 11 turfs treated with heat-killed K. pneumoniae showed any activity and their mean rate of ethylene production (40 nmol h−1 per pot) was significantly lower than that for turfs treated with K. pneumoniae.Using the 'Park'–Turface soil-less model system it was shown that acetylene reducing activity was (i) root associated, (ii) generally highest at a depth of 1–4 cm below the surface, (iii) enhanced by washing excised roots, and (iv) inhibited by surface sterilization of excised roots. Klebsiella pneumoniae was recovered from Turface and roots showing acetylene reducing activity.

Kinetics of first-cutting regrowth of alfalfa plants and nitrogenase activity in a controlled environment with and without added nitrate

1983 ◽  
Vol 61 (9) ◽  
pp. 2405-2409 ◽  
Author(s):  
F. D. H. Macdowall
Keyword(s):  
Dry Matter ◽  
Rhizobium Meliloti ◽  
Nitrogenase Activity ◽  
Radical Change ◽  
N Nutrition ◽  
Meliloti Strain ◽  
Medicago Sativa L ◽  
Reducing Activity ◽  
Acetylene Reducing Activity ◽  
Kinetics Of

Seedlings of Medicago sativa L. cv. Algonquin were grown in vermiculite and nodulated by Rhizobium meliloti strain 102F70 at two lower levels of N, until flowering when the tops were cut off to leave about 10% shoot stubble. Residual shoot dry matter immediately resumed first-order growth and maintained it throughout regrowth to second flowering. The rate constants of shoot regrowth were 34% lower (at 15 mM NO3−), 25% lower (at 1.5 mM NO3− symbiotically), or 220% higher (at zero NO3− symbiotically) than the values for 1 to 4-week-old seedlings, which indicated a radical change in physiology. Root dry matter resumed exponential growth after a 7-day recession and its recovery and yields were independent of N nutrition. The most pronounced minima occurred in the acetylene-reducing activity of nitrogenase, the kinetics of which paralleled root dry matter except that its redevelopment stopped after two-thirds of the regrowth time. The rate coefficient for the redevelopment of nitrogenase activity equalled that for its development during the seedling stage, which suggested unchanged limitations on that process until its redevelopment stopped.

Effects of Inoculation with Different Strains of Azospirillum Brasilense on Wheat Roots Development

1988 ◽  
pp. 181-188 ◽  
Author(s):  
P. Barbieri ◽  
A. Bernardi ◽  
E. Galli ◽  
G. Zanetti
Keyword(s):  
Azospirillum Brasilense ◽  
Wheat Roots ◽  
Different Strains
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