scholarly journals Bacterial IAA-Delivery into Medicago Root Nodules Triggers a Balanced Stimulation of C and N Metabolism Leading to a Biomass Increase

2019 ◽  
Vol 7 (10) ◽  
pp. 403 ◽  
Author(s):  
Roberto Defez ◽  
Anna Andreozzi ◽  
Silvia Romano ◽  
Gabriella Pocsfalvi ◽  
Immacolata Fiume ◽  
...  
Keyword(s):  
Plant Growth ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Soluble Sugars ◽  
Plant Growth Promoting Rhizobacteria ◽  
Nitrogen Fixing ◽  
Genomic Changes ◽  
N Metabolism ◽  
C And N ◽  
Biomass Increase

Indole-3-acetic acid (IAA) is the main auxin acting as a phytohormone in many plant developmental processes. The ability to synthesize IAA is widely associated with plant growth-promoting rhizobacteria (PGPR). Several studies have been published on the potential application of PGPR to improve plant growth through the enhancement of their main metabolic processes. In this study, the IAA-overproducing Ensifer meliloti strain RD64 and its parental strain 1021 were used to inoculate Medicago sativa plants. After verifying that the endogenous biosynthesis of IAA did not lead to genomic changes during the initial phases of the symbiotic process, we analyzed whether the overproduction of bacterial IAA inside root nodules influenced, in a coordinated manner, the activity of the nitrogen-fixing apparatus and the photosynthetic function, which are the two processes playing a key role in legume plant growth and productivity. Higher nitrogen-fixing activity and a greater amount of total nitrogen (N), carbon (C), Rubisco, nitrogen-rich amino acids, soluble sugars, and organic acids were measured for RD64-nodulated plants compared to the plants nodulated by the wild-type strain 1021. Furthermore, the RD64-nodulated plants showed a biomass increase over time, with the highest increment (more than 60%) being reached at six weeks after infection. Our findings show that the RD64-nodulated plants need more substrate derived from photosynthesis to generate the ATP required for their increased nitrogenase activity. This high carbohydrate demand further stimulates the photosynthetic function with the production of molecules that can be used to promote plant growth. We thus speculate that the use of PGPR able to stimulate both C and N metabolism with a balanced C/N ratio represents an efficient strategy to obtain substantial gains in plant productivity.

Manipulation of rhizosphere organisms to enhance glomalin production and C sequestration: Pitfalls and promises

2014 ◽  
Vol 94 (6) ◽  
pp. 1025-1032 ◽  
Author(s):  
F. L. Walley ◽  
A. W. Gillespie ◽  
Adekunbi B. Adetona ◽  
J. J. Germida ◽  
R. E. Farrell
Keyword(s):  
Plant Growth ◽  
Mycorrhizal Fungi ◽  
Plant Growth Promoting Rhizobacteria ◽  
C Sequestration ◽  
Ionization Mass ◽  
Edge Structure ◽  
Organic C ◽  
Soil C ◽  
N Storage ◽  
C And N

Walley, F. L., Gillespie, A. W., Adetona, A. B., Germida, J. J. and Farrell, R. E. 2014. Manipulation of rhizosphere organisms to enhance glomalin production and C-sequestration: Pitfalls and promises. Can. J. Plant Sci. 94: 1025–1032. Arbuscular mycorrhizal fungi (AMF) reportedly produce glomalin, a glycoprotein that has the potential to increase soil carbon (C) and nitrogen (N) storage. We hypothesized that interactions between rhizosphere microorganisms, such as plant growth-promoting rhizobacteria (PGPR), and AMF, would influence glomalin production. Our objectives were to determine the effects of AMF/PGPR interactions on plant growth and glomalin production in the rhizosphere of pea (Pisum sativum L.) with the goal of enhancing C and N storage in the rhizosphere. One component of the study focussed on the molecular characterization of glomalin and glomalin-related soil protein (GRSP) using complementary synchrotron-based N and C X-ray absorption near-edge structure (XANES) spectroscopy, pyrolysis field ionization mass spectrometry (Py-FIMS), and proteomics techniques to characterize specific organic C and N fractions associated with glomalin production. Our research ultimately led us to conclude that the proteinaceous material extracted, and characterized in the literature, as GRSP is not exclusively of AMF origin. Our research supports the established concept that GRSP is important to soil quality, and C and N storage, irrespective of origin. However, efforts to manipulate this important soil C pool will remain compromised until we more clearly elucidate the chemical nature and origin of this resource.

scholarly journals SCREENING OF SOIL BACTERIA FOR PLANT GROWTH PROMOTION ACTIVITIES IN VITRO

2016 ◽  
Vol 4 (1) ◽  
pp. 27 ◽  
Author(s):  
Edi Husen
Keyword(s):  
Plant Growth ◽  
Soil Bacteria ◽  
Phosphate Solubilization ◽  
Azotobacter Vinelandii ◽  
Growth Promotion ◽  
Nitrogenase Activity ◽  
Chelating Agent ◽  
Plant Growth Promoting Rhizobacteria ◽  
Iaa Production

Fourteen isolates of soil bacteria, including two known plant growth promoting rhizobacteria (PGPR) strains, Azotobacter vinelandii Mac 259 and Bacillus cereus UW 85, were tested in vitro. Parameters assessed were indoleacetic acid (IAA) production, phosphate solubilization, dinitrogen fixation, and siderophore (Fe-III chelating agent) production. IAA production was assayed colorimetrically using ferric chlorideperchloric acid reagent. Phosphate-solubilization and siderophore production were tested qualitatively by plating the bacteria in Pikovskaya and chrome azurol S agar, respectively. The ability to fix dinitrogen was measured based on nitrogenase activity of the bacteria by gas chromatography. The results showed that twelve isolates produced IAA, ranged from 2.09 to 33.28 µmol ml-1. The ability to solubilize precipitated phosphate was positively exhibited by four isolates (BS 58, BTS, TCaR 61, and BTCaRe 65). Seven isolates including Mac 259 positively produced siderophore. None of the isolates showed nitrogenase activity. Only one isolate (TS 3) did not exhibit any of the traits tested. Isolate TCeRe 60 and reference strain Mac 259 were found to have IAA- and siderophore-producing traits. Four P-solubilizing bacteria (BS 58, BTS, TCaR 61, and BTCaRe 65) were also IAA- and siderophore-producing bacteria. Potential use of these PGPR isolates needs further test in enhancing plant growth.

Characterization of an ineffective actinorhizal microsymbiont, Frankia sp. EuI1 (Actinomycetales)

1980 ◽  
Vol 26 (9) ◽  
pp. 1072-1089 ◽  
Author(s):  
Dwight Baker ◽  
William Newcomb ◽  
John G. Torrey
Keyword(s):  
Host Range ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Host Cells ◽  
Vesicle Formation ◽  
Nitrogen Fixing ◽  
Elaeagnus Umbellata

The actinomycete, Frankia sp. EuI1, isolated from root nodules of Elaeagnus umbellata is an infective endophyte but which lacks the ability to form an effective nitrogen-fixing symbiosis with its host. This ineffective organism can be distinguished easily from other frankiae, in vitro, on the basis of size, morphology, and the elaboration of a diffusible pigment. Cross-inoculation studies indicated that the host range of this symbiont is narrow and probably restricted to the Elaeagnaceae. In all cases of nodulation the symbiosis never developed nitrogenase activity and the microsymbiont never produced endophytic vesicles within the infected host cells. Sporangia were produced in vivo and in vitro so the morphogenetic block is apparently restricted to vesicle formation.

scholarly journals The Effects of Halomonas sp. and Azotobacter sp. on Ameliorating the Adverse Effect of Salinity in Purple Basil (Ocimum basilicum L.)

2021 ◽  
Author(s):  
Arghavan Salimi ◽  
Mohammad Etemadi ◽  
Saeid Eshghi ◽  
Akbar Karami ◽  
Javad Alizargar
Keyword(s):  
Secondary Metabolites ◽  
Plant Growth ◽  
Salinity Stress ◽  
Growth Parameters ◽  
Soluble Sugars ◽  
Plant Growth Promoting Rhizobacteria ◽  
Nacl Salinity ◽  
Stress Markers ◽  
Negative Effect ◽  
Plant Growth Promoting

The role of plant growth-promoting rhizobacteria (PGPR) on enhancing tolerance of plants to abiotic stresses is well reported, but the effects of RGPRs on plants under salinity stress are not widely studied in the literature. Our study aimed to investigate the effect of Halomonas sp. and Azotobacter sp. on antioxidant activity, secondary metabolites, and biochemicals changes of purple basil under salinity stress conditions. The applied salt concentrations in this study were 50, 100, and 150 mM sodium chloride (NaCl). Salinity stress had a negative effect on plant growth parameters. Moreover, a reduction in some of the osmolytes and oxidative stress markers was observed. Inoculated plants ameliorated the oxidative damage by reducing the hydrogen peroxide (H2O2) contents and by increasing osmolytes (proline, total proteins, and soluble sugars), antioxidant enzymes activities (catalase, ascorbate peroxidase) and secondary metabolites (flavonoids). Overall, among treatments, plants inoculated with Azotobacter showed a better impact on physiological attributes to alleviate the adverse effects of 150 mM NaCl salinity stress on basil growth.

Nitrogenase activity in response to restricted shoot growth in Alnus incana

1983 ◽  
Vol 61 (11) ◽  
pp. 2949-2955 ◽  
Author(s):  
Kerstin Huss-Danell ◽  
Anita Sellstedt
Keyword(s):  
Root Biomass ◽  
Shoot Growth ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Alnus Incana ◽  
Nitrogen Fixing ◽  
Combined Nitrogen ◽  
Carbon Compounds ◽  
Source Sink ◽  
Nitrogen Percentage

In the Alnus–Frankia symbiosis the nitrogen-fixing root nodules are one of the sinks for carbon compounds newly formed in photosynthesis and exported from the leaves (source). The competition for assimilates between shoot tips and root nodules was studied by reducing shoot growth. Cloned plants of Alnus incana (L.) Moench were grown without combined nitrogen in a growth chamber. Shoot growth was inhibited by excision of all buds or by induced dormancy. The experiments showed an increased root biomass in the treated plants, indicating a changed source–sink balance. The treatments never caused an increased nitrogenase activity (C2H2-dependent C2H4 production); rather it was decreased. The nitrogenase activity was always correlated with leaf areas. It was also correlated with growth, which is shown by the similar nitrogen percentage in intact and treated plants.

Microbial priming elicits improved plant growth promotion and nutrient uptake in pea

2016 ◽  
Vol 63 (3) ◽  
pp. 191-207 ◽  
Author(s):  
Shikha Verma ◽  
Anurup Adak ◽  
Radha Prasanna ◽  
Shri Dhar ◽  
Harshwardhan Choudhary ◽  
...  
Keyword(s):  
Plant Growth ◽  
Microbial Biomass Carbon ◽  
Growth Promotion ◽  
Nitrogenase Activity ◽  
Plant Growth Promoting Rhizobacteria ◽  
Microbial Interactions ◽  
Nodule Number ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Major Nutrients

Legume–microbial interactions focus mainly on Rhizobium. The present study aimed to evaluate the plant growth-promoting (PGP) potential of bacterial and cyanobacterial formulations and variety-specific differences following their inoculation in two varieties of pea (Pisum sativum L.), namely Arkel and GP-17. Providencia sp. PW5–Anabaena laxa CW1 treatment was the most promising, with an 11%–76% increase in defense enzyme activity in both varieties. Interestingly, Arkel responded better in terms of nitrogenase activity, which was enhanced several-fold in the inoculated treatments, and exhibited a significant correlation (r = 0.787, 0.778, 0.755; p < 0.05) with shoot length, fresh weight and nodule number per plant, respectively. Nodule number was significantly correlated (r = 0.74, 0.81; p < 0.05) with PAL and PPO activity, respectively, and with microbial biomass carbon, alkaline phosphatase and dehydrogenase activity (r = 0.582, 0.538, 0.666; p < 0.05), respectively. Variety GP-17, however, responded better in terms of increasing the polysaccharide and glomalin content of soil. This study reveals the promise of co-inoculation of PGPRs (plant growth-promoting Rhizobacteria) as synergistic partners for improving plant growth mobilization of major nutrients in pea. However, there is a need to study root exudate patterns to identify promising microbe–variety combinations.

scholarly journals THE FORMATION OF NITROGEN-FIXING ROOT NODULES BУ SOYBEAN PLANTS UNDER THE USE OF POST-EMERGENCE HERBICIDES, PLANT GROWTH REGULATOR AND MІCROFERTILIZER

2015 ◽  
Vol 21 ◽  
pp. 77-81
Author(s):  
R. A. Gutyanskyi
Keyword(s):  
Plant Growth ◽  
Growth Regulator ◽  
Plant Growth Regulator ◽  
Root Nodules ◽  
Yield Potential ◽  
High Yield ◽  
Nitrogen Fixing ◽  
Soybean Yield ◽  
Soybean Plants ◽  
High Yield Potential

The formation of nitrogen-fixing root nodules, plant mass and soybean yield under the use of post-emergence herbicides and their combinations with plant growth regulator Athonic Plus and mіcrofertilizer Nanomix was studied. It was established that application of tank mixtures of post-emergence herbicides had led to the reduction of number and mass of nitrogenfixing nodules on the roots of soybean plants. Application of the Athonic Plus and Nanomix preparations, on the contrary, had promoted studied indices. The maximum soybean yield was observed in the variants with tank mixtures of herbicides Nabob + Fabіan + Mіura and Nabob + Fusillade Forte 150 EC. Combination of Athonic Plus and Nanomix preparations with post-emergence herbicides had resulted in the reduction of the herbicides efficiency against weeds, which had prevented to unleash high yield potential of the crop.

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