Carbon and nitrogen balance in beech roots under competitive pressure of soil-borne microorganisms induced by girdling, drought and glucose application

2010 ◽  
Vol 37 (9) ◽  
pp. 879 ◽  
Author(s):  
Jana B. Winkler ◽  
Michael Dannenmann ◽  
Judy Simon ◽  
Rodica Pena ◽  
Christine Offermann ◽  
...  
Keyword(s):  
Amino Acid ◽  
Feedback Inhibition ◽  
Root Tip ◽  
Pulse Labelling ◽  
Root Tips ◽  
Free Living ◽  
Soil System ◽  
Carbon And Nitrogen ◽  
Fagus Sylvatica L ◽  
Amino Acid Concentrations

The goal of this work was to increase the understanding of factors regulating nitrogen (N) competition between roots and soil microbes. For this purpose, root assimilate supply was diminished or abolished in beech (Fagus sylvatica L.) seedlings by girdling, drought stress or a combination of both factors. This was revealed by 13C tracer abundance in root tips after 13CO2 pulse labelling of the shoots. Analysis of different root tip fractions revealed that only 6% were ectomycorrhizal. Carbon (C) allocation to ectomycorrhizal and vital non-mycorrhizal root tips was ~26% higher than to distorted root tips. Drought resulted in ~30% increased ammonium (NH4+) and amino acid concentrations in roots and ~65% increased soil NH4+ concentrations, probably because of lower consumption of NH4+ by free-living microorganisms. Root uptake of glutamine of 13 nmol g–1 fresh mass h–1 decreased 2-fold with drought, although the number of vital root tips did not decrease. Carbon content in biomass of free-living microbes increased with glucose application regardless of drought, resulting in significant depletion in soil nitrate (NO3–), root NH4+ and amino acid concentrations. Our results suggest that the root–soil system of young beech trees was C-limited, and this prevented amino acid metabolism in roots and microbial NO3– consumption in the soil, thereby exerting feedback inhibition on uptake of inorganic N by roots. We suggest that rhizodeposition is a key link in regulating the plant–microbial N balance.

Cellular Amino Acid Concentrations and Regulation of Aspartate Kinase in the Thermophilic Phototrophic Prokaryote Chloroflexus aurantiacus

1990 ◽  
Vol 45 (1-2) ◽  
pp. 74-78 ◽  
Author(s):  
Jobst-Heinrich Klemme ◽  
Gisela Laakmann-Ditges ◽  
Jutta Mertschuweit
Keyword(s):  
Amino Acid ◽  
Feedback Inhibition ◽  
Gel Filtration ◽  
Break Point ◽  
Test System ◽  
Chloroflexus Aurantiacus ◽  
Aspartate Kinase ◽  
Homoserine Dehydrogenase ◽  
Molecular Weights ◽  
Amino Acid Concentrations

Aspartate kinase (AK , EC 2.7.2.4) from the thermophilic, phototrophic prokaryote, Chloroflexus aurantiacus, was partially purified and separated from homoserine dehydrogenase (HSDH, EC 1.1.1.3). The molecular weights as determined by gel filtration were 130,000 and 46,000, respectively. HSDH had a moderately high thermal stability (50% inactivation at 84 °C) and displayed its activity optimum at 72 °C. By contrast, AK had its activity optimum at 52 °C (with a break-point in the Arrhenius plot at 42 °C) and was much less thermostable (50% inactivation at 67 °C). The Km-values for aspartate and ATP (determined in a pyruvate kinase-coupled test system) were 10.5 and 0.63 mM , respectively. The enzyme was strongly inhibited by L-threonine (Ki = 10 μm) and activated by alanine, isoleucine, valine and methionine. L-Threonine acted as a mixed-type inhibitor in respect to aspartate, and non-competitively in respect to ATP. Contrary to AKs from Rhodospirillaceae, the enzyme from Chloroflexus aurantiacus was not subject to a concerted feedback inhibition by two amino acids of the aspartate family. The regulatory properties of the aspartate kinase are discussed in relation to the cellular amino acid concentrations.

scholarly journals Resilience of soil microbial activity and of amino acid dynamics to the removal of plant carbon inputs during winter

2009 ◽  
Vol 66 (1) ◽  
pp. 132-135 ◽  
Author(s):  
Elizabeth J. Avramides ◽  
Matina Christou ◽  
David L. Jones
Keyword(s):  
Amino Acid ◽  
Free Amino ◽  
Agricultural Soils ◽  
Soil Microbial Activity ◽  
Carbon And Nitrogen ◽  
Soil Microbial ◽  
Heterotrophic Soil Respiration ◽  
Vineyard Soil ◽  
Labile C ◽  
Amino Acid Concentrations

Many temperate agricultural soils have prolonged periods in the winter when plant carbon inputs to the soil are low. Soil maintained at low temperature in the absence of plants was used to simulate the conditions in a vineyard soil during winter. In a four month simulated overwintering period we showed that the concentration of dissolved organic carbon and nitrogen in soil solution slowly declined alongside heterotrophic soil respiration. Measurements of free amino acid concentrations and turnover indicated that the amino acid pool in soil was rapidly depleted but readily replenished throughout the four-month period. This indicates that the soil contained intrinsic reserves of labile C that was capable of supporting the soil microbial community in times of reduced plant C inputs.

scholarly journals Nanotube-mediated cross-feeding couples the metabolism of interacting bacterial cells

2017 ◽  
Author(s):  
Shraddha Shitut ◽  
Tobias Ahsendorf ◽  
Samay Pande ◽  
Matthew Egbert ◽  
Christian Kost
Keyword(s):  
Amino Acid ◽  
Feedback Inhibition ◽  
Bacterial Cells ◽  
Loss Of Function ◽  
E Coli ◽  
Donor Cells ◽  
Mere Presence ◽  
Source Sink ◽  
Amino Acid Concentrations ◽  
Amino Acid Biosynthetic Pathway

ABSTRACTBacteria frequently engage in cross-feeding interactions that involve an exchange of metabolites with other micro- or macroorganisms. The often obligate nature of these associations, however, hampers manipulative experiments, thus limiting our mechanistic understanding of the ecophysiological consequences that result for the organisms involved. Here we address this issue by taking advantage of a well-characterised experimental model system, in which auxotrophic genotypes ofE. coliderive essential amino acid from prototrophic donor cells using intercellular nanotubes. Surprisingly, donor-recipient cocultures revealed that the mere presence of auxotrophic genotypes in coculture was sufficient to increase amino acid production levels in donor cells. Subsequent experiments unravelled that this effect was due to the depletion of amino acid concentrations in the cytoplasm of donor cells, which delayed feedback inhibition of the corresponding amino acid biosynthetic pathway. This finding indicates that in newly established mutualistic associations, an intercellular regulation of exchanged metabolites can simply emerge from the architecture of the underlying biosynthetic pathways, rather than through the evolution of new regulatory mechanisms. Taken together, our results show that a single loss-of-function mutation can physiologically couple the metabolism of two cross-feeding cells in a source-sink-like relationship.

scholarly journals Regulation of Glutamate Dehydrogenases in Neurospora Crassa as a Response to Carbohydrates and Amino Acids in the Media

1971 ◽  
Vol 24 (4) ◽  
pp. 905 ◽  
Author(s):  
WN Strickland
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Sole Carbon Source ◽  
Nitrogen Sources ◽  
Carbon And Nitrogen Sources ◽  
Carbon And Nitrogen ◽  
Acid Accumulation ◽  
The Media ◽  
Amino Acid Concentrations ◽  
Amino Acid Accumulation

Mycelial pads of N. crassa grown for 48 hr in minimal medium were harvested, washed, and transferred to test media containing a variety of carbon and nitrogen sources. When some amino acids served as the sole carbon source, NAD-GDH was induced and the activity of NADP-GDH declined. Addition of sucrose depressed or prevented induction of NAD-GDH while NADP�GDH activity was maintained. Internal amino acid concentrations increased when mycelial pads were incubated in amino acids that induced NAD-GDH, but these accumulated amino acids were only oxidized in the absence of sucrose. The rate of amino acid accumulation decreased if sucrose was present in the media.

Growth, carcass traits, and plasma amino acid concentrations of gilts fed low-protein diets supplemented with amino acids including histidine, isoleucine, and valine

2003 ◽  
Vol 81 (6) ◽  
pp. 1529 ◽  
Author(s):  
J. L. Figueroa ◽  
A. J. Lewis ◽  
P. S. Miller ◽  
R. L. Fischer ◽  
R. M. Diedrichsen
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Carcass Traits ◽  
Plasma Amino Acid ◽  
Low Protein ◽  
Protein Diets ◽  
Amino Acid Concentrations

Histochemical Examination of Invertase Activities in the Growing Tip of the Plant Root

2017 ◽  
Vol 10 (1) ◽  
pp. 35-45
Author(s):  
N.F. Lunkova ◽  
N.A. Burmistrova ◽  
M.S. Krasavina
Keyword(s):  
Plant Root ◽  
Invertase Activity ◽  
Root Tip ◽  
Elongation Zone ◽  
Root Tips ◽  
Phloem Unloading ◽  
Meristem Cell ◽  
Transition To Elongation ◽  
Different Tissues

Background:A growing part of the root is one of the most active sinks for sucrose coming from source leaves through the phloem. In the root, sucrose is unloaded from conducting bundles and is distributed among the surrounding cells. To be involved in the metabolism, sucrose should disintegrate into hexoses by means of degrading enzymes.Aims:The aim of this research was to explore the possibility of the involvement of one such enzymes, invertase, in phloem unloading as well as distribution of its activity in the functionally different tissues of the plant root tips.Method:To estimate the enzyme activities in root tissues, we applied two techniques: the histochemical method using nitro blue tetrazolium. The localization of phloem unloading was studied with carboxyfluorescein, a fluorescent marker for symplastic transport.Results:Invertase activity was not detected in the apical part of the meristem. It appeared only between the basal part of this zone and the beginning of the elongation zone. There is the root phloem unloading in that area. Invertase activity increased with increasing the distance from the root tip and reached the highest values in the region of cell transition to elongation and in the elongation zone. The activities of the enzyme varied in different tissues of the same zone and sometimes in the neighboring cells of the same tissue. Biochemical determination of invertase activity was made in the maize root segments coincident to the zones of meristem, cell elongation and differentiation. The results of both methods of determination of invertase activity were in agreement.Conclusion:It was concluded that phloem unloading correlated with invertase activity, possibly because of the activation of invertase by unloaded sucrose. Invertase is one of the factors involved in the processes preparing the cells for their transition to elongation because the concentration of osmotically active hexoses increases after cleavage of sucrose, that stimulates water entry into the cells, which is necessary for elongation growth.

scholarly journals Effect of earthworms on mycorrhization, root morphology and biomass of silver fir seedlings inoculated with black summer truffle (Tuber aestivum Vittad.)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tina Unuk Nahberger ◽  
Gian Maria Niccolò Benucci ◽  
Hojka Kraigher ◽  
Tine Grebenc
Keyword(s):  
Root System ◽  
Root Biomass ◽  
Fine Root ◽  
Abies Alba ◽  
Fine Root Biomass ◽  
Root Tip ◽  
Silver Fir ◽  
Tuber Aestivum ◽  
Root Tips ◽  
Root Parameters

AbstractSpecies of the genus Tuber have gained a lot of attention in recent decades due to their aromatic hypogenous fruitbodies, which can bring high prices on the market. The tendency in truffle production is to infect oak, hazel, beech, etc. in greenhouse conditions. We aimed to show whether silver fir (Abies alba Mill.) can be an appropriate host partner for commercial mycorrhization with truffles, and how earthworms in the inoculation substrate would affect the mycorrhization dynamics. Silver fir seedlings inoculated with Tuber. aestivum were analyzed for root system parameters and mycorrhization, how earthworms affect the bare root system, and if mycorrhization parameters change when earthworms are added to the inoculation substrate. Seedlings were analyzed 6 and 12 months after spore inoculation. Mycorrhization with or without earthworms revealed contrasting effects on fine root biomass and morphology of silver fir seedlings. Only a few of the assessed fine root parameters showed statistically significant response, namely higher fine root biomass and fine root tip density in inoculated seedlings without earthworms 6 months after inoculation, lower fine root tip density when earthworms were added, the specific root tip density increased in inoculated seedlings without earthworms 12 months after inoculation, and general negative effect of earthworm on branching density. Silver fir was confirmed as a suitable host partner for commercial mycorrhization with truffles, with 6% and 35% mycorrhization 6 months after inoculation and between 36% and 55% mycorrhization 12 months after inoculation. The effect of earthworms on mycorrhization of silver fir with Tuber aestivum was positive only after 6 months of mycorrhization, while this effect disappeared and turned insignificantly negative after 12 months due to the secondary effect of grazing on ectomycorrhizal root tips.

Access to 2-Arylquinazolines via Catabolism/Reconstruction of Amino Acids with Insertion of Dimethyl Sulfoxide

2021 ◽  
Author(s):  
Jin-Tian Ma ◽  
Li-Sheng Wang ◽  
Zhi Chai ◽  
Xin-Feng Chen ◽  
Bo-Cheng Tang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Dimethyl Sulfoxide ◽  
Nitrogen Source ◽  
Carbon And Nitrogen ◽  
First Time

Quinazoline skeletons are synthesized by amino acids catabolism/reconstruction combined with dimethyl sulfoxide insertion/cyclization for the first time. The amino acid acts as a carbon and nitrogen source through HI-mediated catabolism...

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