Transporters for uptake and allocation of organic nitrogen compounds in plants

Rentsch, Doris; Schmidt, Susanne; Tegeder, Mechthild

doi:10.1016/j.febslet.2007.04.013

Cited by 347 publications

(300 citation statements)

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“…Sap composition is known to be affected by the diurnal cycle; for example, in Ricinus communis, there was a diurnal reciprocity between phloem potassium and Suc concentrations (Smith and Milburn, 1980). Amino acids are loaded and unloaded into the ST through transporters, some localized to the vascular tissue (Rentsch et al, 2007). The striking covariation of Tyr, Lys, Phe, Leu/Ile, and His/Val in ST sap observed in this study might be explained by a tight regulation by the diurnal cycle of one or more of these transporters responsible for their loading or retrieval.…”

Section: Discussionmentioning

confidence: 99%

“…A loss-of-function mutation in the amino acid transporter ANT1 led to a change in ST concentration of nine amino acids in Arabidopsis (Hunt et al, 2006); however, only three of those amino acids showed variation in our study, which is inconsistent with the involvement of an ANT1 ortholog in the changes observed in the wheat STs. Amino acid permeases are relatively nonspecific and transport a range of amino acids (Rentsch et al, 2007), but one, or a combination, of them could have higher affinity for a particular subset of amino acids, and their expression or activity could be regulated by a circadian rhythm.…”

Section: Discussionmentioning

confidence: 99%

“…Alongside studies elucidating Suc loading into the ST (for review, see Kü hn, 2003), phloem loading of amino acids has become a subject of great interest, as more than 50 amino acid transporters have been described in Arabidopsis (Arabidopsis thaliana; for review, see Rentsch et al, 2007). The loss of function of ANT1, a member of the aromatic-neutral transporter family, was recently associated with a change in ST amino acid composition in Arabidopsis (Hunt et al, 2006).…”

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confidence: 99%

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A Diurnal Component to the Variation in Sieve Tube Amino Acid Content in Wheat

et al. 2008

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We have used high-sensitivity capillary electrophoresis coupled to a laser-induced fluorescence detection method to quantify 16 amino acids in wheat (Triticum aestivum) sieve tube (ST) samples as small as 2 nL collected by severing the stylets of feeding aphids. The sensitivity of the method was sufficient to determine a quantitative amino acid profile of individual STs without the need to bulk samples to produce larger volumes for analysis. This allowed the observation of the full range of variation that exists in individual STs. Some of the total concentrations of amino acids recorded are higher than those reported previously. The results obtained show variation in the concentrations of phenylalanine (Phe), histidine/valine (His/Val), leucine/ isoleucine (Leu/Ile), arginine, asparagine, glutamine, tyrosine (Tyr), and lysine (Lys) across the ST samples. These could not be explained by plant-to-plant variation. Statistical analyses revealed five analytes (Tyr, Lys, Phe, His/Val, and Leu/Ile) that showed striking covariation in their concentrations across ST samples. A regression analysis revealed a significant relationship between the concentrations of Tyr, Lys, Phe, Leu/Ile, His/Val, asparagine, arginine, and proline and the time of collection of ST samples, with these amino acids increasing in concentration during the afternoon. This increase was confirmed to occur in individual STs by analyzing samples obtained from stylet bundles exuding for many hours. Finally, an apparent relationship between the exudation rate of ST sap and its total amino acid concentration was observed: samples containing higher total amino acid concentrations were observed to exude from the severed stylet bundles more slowly.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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A Diurnal Component to the Variation in Sieve Tube Amino Acid Content in Wheat

et al. 2008

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“…see review by: Hutchinson and Miller 1912). More recent studies have identified in diverse taxa the transporters for organic N compounds including amino acids (Wipf et al 2002;Rentsch et al 2007;Näsholm et al 2009), quaternary ammonium compounds (Breitkreuz et al 1999) and amines + polyamines (Igarashi and Kashiwagi 2010). Finally, injecting soil with organic N compounds in which C and/or N are isotope labeled (e.g.…”

Section: Introductionmentioning

confidence: 99%

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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“…Our understanding of the mechanism by which organic N enters plant cells and is assimilated is quite limited relative to uptake of nitrate and ammonium. There are numerous amino acid transporters belonging to multiple families (Rentsch et al, 2007), yet few have been functionally characterized. Only a handful of studies have investigated how acquired amino acids are assimilated into the N pathway (Schmidt & Stewart, 1999;Thornton & Robinson, 2005;Persson et al, 2006).…”

Section: Nitrogen Uptake and Assimilationmentioning

confidence: 99%