Ammonium Uptake by Rice Roots (III. Electrophysiology)

Wang, Miao Yuan; Glass, Anthony D. M.; Shaff, Jon E.; Kochian, Leon V.

doi:10.1104/pp.104.3.899

Cited by 142 publications

(93 citation statements)

References 14 publications

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“…This is in line with our observations. An ammonium-induced depolarization has also been reported for membrane potentials of root hair cells of barley and tomato seedlings (Ayling 1993) and individual epidermal and cortex cells of intact rice roots (Wang et al 1994). The ammonium effect can be ascribed to ammonium uptake via ion channels and/or specific carriers (Ninnemann, Jauniaux & Frommer 1994).…”

Section: Discussionmentioning

confidence: 95%

“…In order to manipulate the membrane potential of root cortical cells in a defined way, we kept the plants in an N-free 'low salt' medium and made use of the welldocumented response of these cells to an addition of nitrate and ammonium to the bath (McClure et al 1990a;Wang et al 1994). Under these conditions, membrane potential changes can definitely be attributed to transport processes at the plasma membrane rather than to effects on the cell wall potential.…”

Section: Introductionmentioning

confidence: 99%

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Trans‐root potential, xylem pressure, and root cortical membrane potential of ‘low‐salt’ maize plants as influenced by nitrate and ammonium

Wegner

Sattelmacher

Läuchli

et al. 1999

Plant Cell & Environment

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Upon addition of nitrate and ammonium, respectively, to the bath of intact 'low salt' maize plants, the cortical membrane potential and the trans-root potential changed in a similar and synchronous way as revealed by applying conventional microelectrode techniques and the xylem pressure-potential probe (Wegner & Zimmermann 1998). Upon addition of nitrate, a hyperpolarization response was observed which was frequently preceded by a short depolarization phase. In contrast, addition of ammonium resulted in an overall depolarization response both of the cortical membrane potential and the trans-root potential. The nitrate-induced hyperpolarization response and the depolarization following the addition of ammonium were concentration-dependent.The data suggest that a tight electrical coupling exists between the cellular and tissue level in the root of the intact plant and that the resistance of the cellular (symplastic) space is much less than the resistance of the apoplast.

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Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Trans‐root potential, xylem pressure, and root cortical membrane potential of ‘low‐salt’ maize plants as influenced by nitrate and ammonium

Wegner

Sattelmacher

Läuchli

et al. 1999

Plant Cell & Environment

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“…However, other potential signals, such as general cation responses, acidification of the cytosol, or plasma membrane depolarization, could act as signals. Since other ions, such as NO 3 2 , also lead to a depolarization of the plasma membrane but not to phosphorylation ( Figure 3A; Wang et al, 1994;Miller et al, 2001), and since membrane depolarization by 50 mM ammonium is comparatively low (Ayling, 1993), we conclude that plasma membrane depolarization by ammonium is probably insufficient for triggering AMT1-phosphorylation at T460. To analyze the specificity of the response to ammonium, various monovalent cations were tested, including the AMT1 substrate analog methylammonium.…”

Section: Specificity For Ammonium As the Signalmentioning

confidence: 98%

Feedback Inhibition of Ammonium Uptake by a Phospho-Dependent Allosteric Mechanism inArabidopsis

et al. 2009

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The acquisition of nutrients requires tight regulation to ensure optimal supply while preventing accumulation to toxic levels. Ammonium transporter/methylamine permease/rhesus (AMT/Mep/Rh) transporters are responsible for ammonium acquisition in bacteria, fungi, and plants. The ammonium transporter AMT1;1 from Arabidopsis thaliana uses a novel regulatory mechanism requiring the productive interaction between a trimer of subunits for function. Allosteric regulation is mediated by a cytosolic C-terminal trans-activation domain, which carries a conserved Thr (T460) in a critical position in the hinge region of the C terminus. When expressed in yeast, mutation of T460 leads to inactivation of the trimeric complex. This study shows that phosphorylation of T460 is triggered by ammonium in a time-and concentration-dependent manner. Neither Gln nor L-methionine sulfoximine-induced ammonium accumulation were effective in inducing phosphorylation, suggesting that roots use either the ammonium transporter itself or another extracellular sensor to measure ammonium concentrations in the rhizosphere. Phosphorylation of T460 in response to an increase in external ammonium correlates with inhibition of ammonium uptake into Arabidopsis roots. Thus, phosphorylation appears to function in a feedback loop restricting ammonium uptake. This novel autoregulatory mechanism is capable of tuning uptake capacity over a wide range of supply levels using an extracellular sensory system, potentially mediated by a transceptor (i.e., transporter and receptor).

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“…By considering active uptake in addition to passive uptake for NH 4 + -N, contrary to considering only passive uptake for NO 3 − -N, we could ensure that NH 4 + -N uptake accounts for approximately 75% of the total N uptake (Kirk and Kronzucker, 2005;Li et al, 2006). The Michaelis-Menten constant for the active uptake of NH 4 + was assumed equal to 0.31 mg L −1 (Wang et al, 1994;Duan et al, 2007).…”

Section: Soil Depth (Cm)mentioning

confidence: 99%

Evaluation of nitrogen balance in a direct-seeded-rice field experiment using Hydrus-1D

Šimůnek

Zhang

et al. 2015

Agricultural Water Management

118

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a b s t r a c tNitrogen (N) pollution is a global environmental problem that has greatly increased the risks of both the eutrophication of surface waters and contamination of ground waters. The majority of N pollution mainly comes from agricultural fields, in particular during rice growing seasons. In recent years, a gradual shift from the transplanting rice cultivation method to the direct seeding method has occurred, which results in different water and N losses from paddy fields and leads to distinct impacts on water environments. The N transport and transformations in an experimental direct-seeded-rice (DSR) field in the Taihu Lake Basin of east China were observed during two consecutive seasons, and simulated using Hydrus-1D model. The observed crop N uptake, ammonia volatilization (AV), N concentrations in soil, and N leaching were used to calibrate and validate the model parameters. The two most important inputs of N, i.e., fertilization and mineralization, were considered in the simulations with 220 and 145.5 kg ha −1 in 2008 and 220 and 147.8 kg ha −1 in 2009, respectively. Ammonia volatilization and nitrate denitrification were the two dominant pathways of N loss, accounting for about 16.0% and 38.8% of the total N input (TNI), respectively. Both nitrification and denitrification processes mainly occurred in the root zone. N leaching at 60 and 120 cm depths accounted for about 6.8% and 2.7% of TNI, respectively. The crop N uptake was 32.1% and 30.8% of TNI during the 2008 and 2009 seasons, respectively, and ammonium was the predominant form (74% of the total N uptake on average). Simulated N concentrations and fluxes in soil matched well with the corresponding observed data. Hydrus-1D could simulate the N transport and transformations in the DSR field, and could thus be a good tool for designing optimal fertilizer management practices in the future.

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Ammonium Uptake by Rice Roots (III. Electrophysiology)

Cited by 142 publications

References 14 publications

Trans‐root potential, xylem pressure, and root cortical membrane potential of ‘low‐salt’ maize plants as influenced by nitrate and ammonium

Trans‐root potential, xylem pressure, and root cortical membrane potential of ‘low‐salt’ maize plants as influenced by nitrate and ammonium

Feedback Inhibition of Ammonium Uptake by a Phospho-Dependent Allosteric Mechanism inArabidopsis

Evaluation of nitrogen balance in a direct-seeded-rice field experiment using Hydrus-1D

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