Diffusion and Absorption of Ions in Plant Tissue I. Observations on the Absorption of Ammonium by Cut Discs of Potato Tuber as Compared to Maize Roots

Honert, T. H. Van Den; Hooymans, J. J. M.

doi:10.1111/j.1438-8677.1961.tb00053.x

Cited by 17 publications

(4 citation statements)

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“…Published reports claim that ammonium uptake by plant roots is mediated by a single component (Becking 1956, van der Honert and Hooymans 1961, Tromp 1962, Lycklama 1963, two components (Berlier et al 1969) or a single multiphasic component (Joseph et al 1975). In the present study, ammonium uptake followed Michaelis-Menten uptake kinetics with only one Km and one V^ax at concentrations ranging from 5 to 100 |xM ammonium in the temperature range from 10 to 35°C (Tab.…”

Section: Discussionmentioning

confidence: 99%

Uptake of ammonium and nitrate by carob (Ceratonia siliqua) as affected by root temperature and inhibitors

Cruz

Lips

Martins-Loução

1993

Physiologia Plantarum

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Cruz, C, Lip.s. S. H. and Martins-Lou9ao, M. A. 1993. Uptake of ammonium and nitrate by carob {Ceratonia siliqua) as affected by root temperature and inhibitors. -Physiol. Plant. 89: 532-543.Seedlings of carob {Ceratonia siliqua L. cv. Mulata) were grown in nutrient solution culture for 5 weeks, with or without nitrogen at different root temperatures (10. 16. 22, 30, 35 or 40°C) and with the air temperature kept between 20 and 24°C. The nitrogen was given as either ammonium or nitrate. At all root temperatures studied, nitrogendepleted plants developed higher net uptake rates for nitrogen than plants grown in the presence of nitrogen. Temperature affected the kinetic parameters of nitrate uptake more than those of ammonium uptake. With increasing root temperature, the K^ of ammonium uptake decreased, but to a lesser extent than the K,^ for nitrate. The increase in Vn,a^ of ammonium uptake with temperature was also less noticeable than that for nitrate uptake. Ammonium and nitrate uptakes were inhibited in a similar way by respiratory or protein synthesis inhibitors. It rnay be noted that ammonium uptake in the presence of inhibitors at 40°C was higher than uptake at 10°C without inhibitors. Some similarities between the transport mechanisms for nitrate and ammonium are underlined in the present work. Components of both transport systems displayed saturation kinetics and depended on protein synthesis and energy. The following components of nitrate uptake were distinguished: (a) a passive net influx into the apparent free space: (b) a constitutive active uptake and (c) active uptake dependent on protein synthesis. We may similarly define three ammonium uptake systems: (a) a passive influx into the apparent free space; (b) passive diffusion uptake at high temperature and (c) active uptake dependent on protein synthesis. The possible role of the ratio between mechanism (c) and mechanism (b) as determinant of ammonium sensitivity is discussed.

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Section: Discussionmentioning

confidence: 99%

Uptake of ammonium and nitrate by carob (Ceratonia siliqua) as affected by root temperature and inhibitors

Cruz

Lips

Martins-Loução

1993

Physiologia Plantarum

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“…For example, NO3 uptake has been described as resembling a single (19,29), dual (10, 23), single multiphasic (5) isotherm or the additive result of one saturable plus one nonsaturable, linear component (14). Similarly, NH4+ transport was mediated by a single (2,19,28,30), two different (3), and a single multiphasic transport system (18). K,n values (Michaelis constant) for transport of these ions also differ substantially: a range of 0.001 to 7.5 mm for NO3-and 0.007 to 3.0 mm for NH4' have been published previously.…”

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“…Published reports show that NH4+ uptake by plant roots is mediated by a single (2,19,28,30), or two different (3), or a single multiphasic mechanism (18). In the present study, NH4+ uptake kinetics resembled a single Langmuir isotherm in a concentration range of 0 to 1 mM with saturation achieved at about 0.3 mm (Fig.…”

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confidence: 99%

The Uptake of NO₃⁻, NO₂⁻, and NH₄⁺ by Intact Wheat (Triticum aestivum) Seedlings

Goyal¹,

Huffaker²

1986

Plant Physiol.

124

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The inducibility and kinetics of the NO3-, NO2-, and NH4+ transporters in roots of wheat seedlings (Triticum aestivum cv Yercora Rojo) were characterized using precise methods approaching constant analysis of the substrate solutions. A microcomputer-controlled automated high performance liquid chromatography system was used to determine the depletion of each N species (initially at 1 millimolar) from complete nutrient solutions. Uptake rate analyses were performed using computerized curve-fitting techniques. More precise estimates were obtained for the time required for and the extent of the induction of each transporter. Up to 10 and 6 hours, respectively, were required to achieve apparent full induction of the N03-and NO2-transporters. Evidence for substrate inducibility of the NH4+ transporters requiring 5 hours is presented. The transport of N03-was mediated by a dual system (or dual phasic), whereas only single systems were found for transport of NO2-and NH4+.The K. values for N03-, NO2-, and NH4I were, respectively, 0.027, 0.054, and 0.05 millimolar. The K,,, for mechanism II of NO3-transport could not be defined in this study as it exhibited only apparent first order kinetics up to I millimolar.Apparent substrate inducibility of a root NO3-transporter in many higher plants has been known for over a decade (16). The reported induction periods required to achieve a steady state uptake rate differ: 1 to 2 h, corn roots (22); 3 to 4 h, barley seedlings (23); 4 h, wheat seedlings (16); 6 to 7 h, dwarf bean seedlings (5). Much less work has been done on the induction of a NO; transporter; its apparent induction by NO;2, requiring about 4 h, has been reported (17). Ammonium uptake by plant roots during early exposure to NH4' has been characterized as an initial brief phase of rapid uptake confounded by free space and ion exchange, followed by a slower linear rate (20). Information on substrate inducibility of the NH4+ transporter has not been previously reported.The uptake of inorganic N species during the induction of their transporters is a dynamic process with an increasing catalyst and a decreasing ion concentration in the ambient solution. The resultant uptake during that time requires further definition. It is important to characterize the induction phase of a transporter since it should be fully induced before evaluating kinetic parameters. ' Supported in part by a grant from the United States National Aeronautics and Space Agency (NASA NCC 2-99).Conclusions about the induction periods have often been based on accumulative uptake as a function of time. This method does not offer the degree of resolution required to precisely define the extent of induction or the time required for full induction. Small changes in uptake rates are masked in such plots. A rate analysis as a function of time allows a higher resolution of the induction of a transporter. This requires a sensitive and precise analytical method to establish rates over small changes in concentration of the ambient solution. A microcompute...

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“…Concentrations at which plants benefit from NH4' absorption are narrow, however, and excess levels can produce toxic reactions (4). This limits the use of NH4' as a source of nitrogen for most plants.Ammonium absorption kinetics have been observed in a number of higher plants (1,10,12,17,20,21) including soybean (9). A comparative study on the kinetics of NH4' absorption by nodulated and unnodulated soybeans would furnish information on the uptake mechanism and would describe the uptake pattern of plants dependent on N2 fixation as a source of N. Ammonium ion concentration (9, 10, 12), root and shoot temperature (3, 7, 10), solution pH (1,10,14,20), and other ions (10, 14) influence short-term NH4' absorption.…”

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Simultaneous Measurement of NH₄⁺ Absorption and N₂ Fixation by Glycine max L.

Marcus‐Wyner¹,

Rains²

1982

Plant Physiol.

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Ammonium absorption rates by intact nodulated and unnodulated soybean plants (Grycie max IL.l Meff., Amsoy 71) were determined from the lquid phase of a mist assay chamber. From the gas phase, simultaneous measurements of acetylene reductio rates were made from nodulated plants. Ammonium absorption capacity was consistently greater in unnodulated plants.At the bnnig of flowering, plant roots were sprayed with an uptake solution ranging from 0.05 to 1.0 milUmolar NH4Cl, and root nodules concurrently were exposed to 0.12 atmosphere acetylene. The NH4' absorption system of both nodulated and unnodulated plants were nearly saturated at 0.3 to 0.5 millimolar NH4+.Increasing the pH from 4.0 to 6.8 stimulated NH4+ absorption rate in both flowering and preilowering nodulated and unnodulated plants. Acet The interaction between N2 fixation and inorganic N in leguminous plants has been the object ofmany studies (5, 15). Longterm experiments which quantify mineral composition and yield responses have led to insights on how N source and time of N application influence N2 fixation. Short-term studies are aimed at characterization of control mechanisms and the specific influence of various parameters. Since N03 is the predominant ionic form of N in the soil solution, most work has focused on the interaction of N03 and N2 fixation. Realization of the need to increase N use efficiency due to both economic and environmental concerns, coupled with the availability ofnitrification inhibitors, has aroused interest in the role of NH4' in this interaction.Initially, it appears that metabolic energy would be conserved if NH4' was supplied to the roots, since the processes of N2 fLxation and NO3 absorption and reduction require large amounts of reductant and ATP (19 incorporated into organic compounds without the expenditure of energy for reduction. Concentrations at which plants benefit from NH4' absorption are narrow, however, and excess levels can produce toxic reactions (4). This limits the use of NH4' as a source of nitrogen for most plants.Ammonium absorption kinetics have been observed in a number of higher plants (1,10,12,17,20,21) including soybean (9). A comparative study on the kinetics of NH4' absorption by nodulated and unnodulated soybeans would furnish information on the uptake mechanism and would describe the uptake pattern of plants dependent on N2 fixation as a source of N. Ammonium ion concentration (9, 10, 12), root and shoot temperature (3, 7, 10), solution pH (1,10,14,20), and other ions (10, 14) influence short-term NH4' absorption. Similar to NH4' absorption, the N2 fixing activity of root nodules is influenced by temperature (8,15,18), pH (15), and combined N (5, 15).Most conventional techniques measure N2 (acetylene) fixation3by incubating root systems in the gas phase of a solid rooting medium. In contrast, ion absorption is measured by ion depletion from substrate media or by accumulation in plant tissues. However, N2 fixation and ion absorption do not occur totally independently in the plant. The i...

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Diffusion and Absorption of Ions in Plant Tissue I. Observations on the Absorption of Ammonium by Cut Discs of Potato Tuber as Compared to Maize Roots

Cited by 17 publications

References 9 publications

Uptake of ammonium and nitrate by carob (Ceratonia siliqua) as affected by root temperature and inhibitors

Uptake of ammonium and nitrate by carob (Ceratonia siliqua) as affected by root temperature and inhibitors

The Uptake of NO₃⁻, NO₂⁻, and NH₄⁺ by Intact Wheat (Triticum aestivum) Seedlings

Simultaneous Measurement of NH₄⁺ Absorption and N₂ Fixation by Glycine max L.

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Diffusion and Absorption of Ions in Plant Tissue I. Observations on the Absorption of Ammonium by Cut Discs of Potato Tuber as Compared to Maize Roots

Cited by 17 publications

References 9 publications

Uptake of ammonium and nitrate by carob (Ceratonia siliqua) as affected by root temperature and inhibitors

Uptake of ammonium and nitrate by carob (Ceratonia siliqua) as affected by root temperature and inhibitors

The Uptake of NO3−, NO2−, and NH4+ by Intact Wheat (Triticum aestivum) Seedlings

Simultaneous Measurement of NH4+ Absorption and N2 Fixation by Glycine max L.

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The Uptake of NO₃⁻, NO₂⁻, and NH₄⁺ by Intact Wheat (Triticum aestivum) Seedlings

Simultaneous Measurement of NH₄⁺ Absorption and N₂ Fixation by Glycine max L.