Characteristics of amino acid uptake in barley

Jämtgård, Sandra; Näsholm, Torgny; Huss‐Danell, Kerstin

doi:10.1007/s11104-007-9473-4

Cited by 80 publications

(53 citation statements)

References 38 publications

(68 reference statements)

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“…Concentrations of amino acids at steady-state and rates of efflux were, in fact, broadly similar to those reported in previous studies focusing solely on amino acids (Jones and Darrah 1993;Phillips et al 2006;Lesuffleur et al 2007;Jämtgård et al 2008; Cliquet Fig. 6 The multivariate relationships among H 2 O extracts of roots, the aqueous phase of a methanol:chloroform:water extract of roots and the concentration of exudates measured at 4 h (a) and also the gross rate of efflux calculated between 1 min and 1 h (b).…”

Section: Discussionsupporting

confidence: 82%

“…Indeed, many studies on organic N compounds have focussed solely on amino acids (Jones and Darrah 1993;Phillips et al 2006;Lesuffleur et al 2007;Jämtgård et al 2008;Lesuffleur and Cliquet 2010), while reviews and summaries often imply that amino acids are the main organic N compound in root exudates. For example, the chemical composition of root exudates has been summarised as: sugars (50-70 % of exudate), carboxylic acids (20-30 % of exudate) and amino acids (10-20 % of exudate) (Kraffczyk et al 1984;Jones 1998;Hutsch et al 2002;Farrar et al 2003).…”

Section: Discussionmentioning

confidence: 99%

“…In the context of re-capture of effluxed compounds, use of realistically low compound concentrations is vitally important given that uptake of organic N compounds is concentration dependent (e.g. amino acids: Schobert and Komor 1987;Jämtgård et al 2008). In this context it is worth noting that past studies showing simultaneous efflux and re-capture of amino acids supplied amino acids at arbitrary concentrations of 1 10 & 20 μM (Lesuffleur et al 2007; Lesuffleur and Cliquet 2010) or 2.5 μM (Phillips et al 2004(Phillips et al , 2006 or 100 μM (Jones and Darrah 1994).…”

mentioning

confidence: 99%

“…Samples of hydroponic solution were collected immediately before plants were added (T0), then 1 min, 1, 2 and 4 h after plants were added. An additional experiment involving Binterrupted uptake^ (Jämtgård et al 2008) was performed to verify that the changes in compound concentrations were due to plants rather than exoenzymes or microbial contamination. The experiment was carried out as described above, except that at 1 h plants were removed.…”

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confidence: 99%

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Wheat roots efflux a diverse array of organic N compounds and are highly proficient at their recapture

Warren

2015

Plant Soil

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Background & aims Small organic N compounds could contribute to N nutrition, but an alternative view is that root uptake may serve to recapture compounds that efflux out of roots. However, it is unclear if plants can recapture leaked organic N compounds because no studies have examined quantitative relationships between efflux and uptake at sub-micromolar concentrations. Methods This study examines efflux and uptake of a broad suite of small organic N compounds by wheat (Triticum aestivum L.).15 N-labeling and capillary electrophoresis-mass spectrometry were used to estimate efflux and uptake. Results One hundred and ten organic N compounds were detected in exudates. Amino acids were abundant but accounted for less than half of organic N. Other abundant compound classes were amines and polyamines, quaternary ammonium compounds, nucleobases and nucleosides. Uptake occurred simultaneously with efflux for all 45 compounds for which rates of efflux could be reliably determined, even though concentrations were 0.01 to 0.5 μM.Conclusions These findings indicate that wheat is highly proficient at recapturing much of the diverse array of organic N compounds in root exudates. The ability to salvage effluxed compounds present at very low concentrations means that wheat might also be able to take up organic N compounds from the soil solution.

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Section: Discussionsupporting

confidence: 82%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Wheat roots efflux a diverse array of organic N compounds and are highly proficient at their recapture

Warren

2015

Plant Soil

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“…The concentration of amino acids in the soil solution ranges from 0.1 to 60 µM and typically constitutes 10-40 % of the total soluble N (Hill et al, 2011;Jamtgard et al, 2008;Jones et al, 2002). The pool of dissolved amino acids is supplemented by a substantial pool of absorbed amino acids which can be up to 50 times higher than the amount of free amino acids and, in unfertilized soils, even higher than the content of ammonium and nitrate (Jamtgard et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Interactions between uptake of amino acids and inorganic nitrogen in wheat plants

2012

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Abstract. Soil-borne amino acids may constitute a source of nitrogen (N) for plants in various terrestrial ecosystems but their importance for total N nutrition is unclear, particularly in nutrient-rich arable soils. One reason for this uncertainty is lack of information on how the absorption of amino acids by plant roots is affected by the simultaneous presence of inorganic N forms. The objective of the present study was to study absorption of glycine (Gly) and glutamine (Gln) by wheat roots and their interactions with nitrate (NO − 3 ) and ammonium (NH + 4 ) during uptake. The underlying hypothesis was that amino acids, when present in nutrient solution together with inorganic N, may lead to down-regulation of the inorganic N uptake, thereby resulting in similar total N uptake rates. Amino acids were enriched with double-labelled 15 N and 13 C, while NO − 3 and NH + 4 acquisition was determined by their rate of removal from the nutrient solution surrounding the roots. The uptake rates of NO − 3 and NH + 4 did not differ from each other and were generally about twice as high as the uptake rate of organic N when the different N forms were supplied separately in concentrations of 2 mM. Nevertheless, replacement of 50 % of the inorganic N with organic N was able to restore the N uptake to the same level as that in the presence of only inorganic N. Co-provision of NO − 3 did not affect glycine uptake, while the presence of glycine down-regulated NO − 3 uptake. The ratio between 13 C and 15 N were lower in shoots than in roots and also lower than the theoretical values, reflecting higher C losses via respiratory processes compared to N losses. It is concluded that organic N can constitute a significant N-source for wheat plants and that there is an interaction between the uptake of inorganic and organic N.

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Vertical Stratification of Peat Pore Water Dissolved Organic Matter Composition in a Peat Bog in Northern Minnesota

et al. 2018

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We characterized dissolved organic matter (DOM) composition throughout the peat column at the Marcell S1 forested bog in northern Minnesota and tested the hypothesis that redox oscillations associated with cycles of wetting and drying at the surface of the fluctuating water table correlate with increased carbon, sulfur, and nitrogen turn over. We found significant vertical stratification of DOM molecular composition and excitation‐emission matrix parallel factor analysis components within the peat column. In particular, the intermediate depth zone (~ 50 cm) was identified as a zone where maximum decomposition and turnover is taking place. Surface DOM was dominated by inputs from surface vegetation. The intermediate depth zone was an area of high organic matter reactivity and increased microbial activity with diagenetic formation of many unique compounds, among them polycyclic aromatic compounds that contain both nitrogen and sulfur heteroatoms. These compounds have been previously observed in coal‐derived compounds and were assumed to be responsible for coal's biological activity. Biological processes triggered by redox oscillations taking place at the intermediate depth zone of the peat profile at the S1 bog are assumed to be responsible for the formation of these heteroatomic PACs in this system. Alternatively, these compounds could stem from black carbon and nitrogen derived from fires that have occurred at the site in the past. Surface and deep DOM exhibited more similar characteristics, compared to the intermediate depth zone, with the deep layer exhibiting greater input of microbially degraded organic matter than the surface suggesting that the entire peat profile consists of similar parent material at different degrees of decomposition and that lateral and vertical advection of pore water from the surface to the deeper horizons is responsible for such similarities. Our findings suggest that molecular composition of DOM in peatland pore water is dynamic and is a function of ecosystem activity, water table, redox oscillation, and pore water advection.

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Characteristics of amino acid uptake in barley

Cited by 80 publications

References 38 publications

Wheat roots efflux a diverse array of organic N compounds and are highly proficient at their recapture

Wheat roots efflux a diverse array of organic N compounds and are highly proficient at their recapture

Interactions between uptake of amino acids and inorganic nitrogen in wheat plants

Vertical Stratification of Peat Pore Water Dissolved Organic Matter Composition in a Peat Bog in Northern Minnesota

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