Ionic Balance in Different Tissues of the Tomato Plant in Relation to Nitrate, Urea, or Ammonium Nutrition

Kirkby, Ernest A.; Mengel, K.

doi:10.1104/pp.42.1.6

Cited by 390 publications

(242 citation statements)

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“…Acid-base balance during growth demands an H+ efflux of 4/3 H+ per NH/ entering and assimilated (see Raven, 1985Raven, a, 1986Raven, , 19876, 1988. Consideration of SO42-and H2PO4" uptake and assimilation reduces the net H"^ efflux to 1-22 H^ per N assimilated, although the net negative charge on organic matter remains at 0-33 mol negative charge per mol N or 0-022 mol negative charge per mol C. Kirkby & Mengel (1967) report some 0-17 mol negative charge on uronate per mol N, or 0-011 mol negative charge on uronate per mol C. As mentioned in Section II, this negative charge arises by oxidation of reduced C derived from Rubisco-catalysed CO2 fixation, so does not involve non-Rubisco carboxylases. The remaining organic negative charge is borne mainly by low M^ carboxylic acids, and that not more than half of this negative charge is the result of PEPC activity.…”

Section: ^-(7)mentioning

confidence: 98%

The influence of N metabolism and organic acid synthesis on the natural abundance of isotopes of carbon in plants

1990

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SUMMARY This paper relates the 13C/12C ratio of C3 plant material relative to that of source CO2 to the N source for growth, the organic N content of the plant, and the extent of organic acid synthesis. The 13C/12C ratio is quantified as Δ, defined as (δ13C substrate –δ13C product)/(1+δ13C product), where δ13C values of substrate or product (i.e. the samples) are defined as [13C/12C]sample]/[(13C/12C)standard]−1. The computation is performed by relating differences in plant composition as a function of N nutrition and acid synthesis to the fraction of plant C which is acquired via Rubisco and via other carboxylases. The fractional contribution of the different carboxylases to C gain is then related, using the known isotopic fractionations exhibited by these carboxylases, in a model to predict the final Δ of the plant (relative to atmospheric CO2). Application of this approach to a ‘typical’ C3 land plant yields predictions of the decrease of Δ relative to a hypothetical case in which all C is fixed via Rubisco. The predicted decreases range from 0–24 %, for NH4+ assimilation (which always occurs in the roots) to 2–80%, for NO3− assimilation in shoots with the organic acid salt which results from acid‐base balance, plus any additional organic acid salts plus free acids for a plant with a basal C:N molar ratio in organic material of 15. Intermediate values are predicted for symbiotic growth with N2, or where NO3− assimilation in root or shoot is accompanied by some acid‐base regulation via OH‐ loss to the root medium. Comparison with published data on the difference in Δ of Ricinus communis cultured with NH4+ or NO3− shows that the measured influence of nitrogen source is in the right direction (NO3− grown plants with a smaller Δ, i.e. a larger deviation from the value predicted for the absence of non‐Rubisco carboxylations) to be explained by the observed difference in composition and hence fractional C contribution by the various carboxylases. However, the effect of N source on Δ is greater than that predicted by the model, i.e. a 2.1 % decrease as opposed to a 0.10 % decrease. It is likely that the major cause of the difference in δ13C of the plants grown on the two N sources is a change in the ratio of transport and biochemical conductances of leaf photosynthesis. Such a change is quantitatively consistent with the lower water use efficiency of NH4+ ‐grown plants. The predicted, and observed, changes in Δ as a function of N source are of the same magnitude as those found for C3 terrestrial species grown at different temperatures or photon flux densities, or in environments yielding different water use efficiencies by changing root water supply relative to shoot evaporation potential. Variations in N source should be added to the factors which might alter δ of plants growing in the field.

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Section: ^-(7)mentioning

confidence: 98%

The influence of N metabolism and organic acid synthesis on the natural abundance of isotopes of carbon in plants

1990

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“…With the uptake of a large quantity of NH 4 Vertical arrows indicate the membrane permeability threshold below which the net changes in the cation concentrations were not responsive to membrane permeability, and above which they showed a gradual increase with increasing membrane permeability ions into the cell, there will be a change in the electrochemical gradient between the cytosol and medium, which needs to be counteracted by simultaneous absorption of anions and/or by ex truding cations out of the cytosol. Therefore, uptake of NH 4 + ions is generally accompanied by changes in the anion and cation content of the culture medium that depend on the cation−anion balance in the cytosol (Kirkby & Mengel 1967). This is probably why an increase in the supply of one ion species in the culture solution decreases the uptake of other ion species with a similar charge when there is no specific competition for a carrier site (Lohaus et al 2000, Shi & Sheng 2005.…”

Section: Discussionmentioning

confidence: 99%

“…uncoupling of photophosphorylation, inhibiting photosynthesis, triggering oxidative stress, causing internal carbon− nitrogen imbalance (Gibbs & Calo 1959, Rudolph & Voigt 1986, Cao et al 2004, Nimptsch & Pflugmacher 2007, Wang et al 2008) and changing cation−anion relationships in the plants (Kirkby & Mengel 1967, Santa-María et al 2000, Szczerba et al 2006. NH 4 + -fed plants have been shown to have lower sodium (Na + ), potassium (K + ), magnesium (Mg 2+ ) and calcium (Ca 2+ ) contents (Kirkby & Mengel 1967, Langelaan & ) concentrations are reported to be an important cause of decline in submersed macrophytes in eutrophic lakes.…”

Section: Introductionmentioning

confidence: 99%

“…Apical shoots of the plants were incubated in modified Hoagland solution with 0. 25, 0.5, 1, 2, 4, 8, 16, 32, 64 and 128 mg l −1 NH 4 + -N for 4 d. The plants were then collected for examination of cell membrane permeability and the solutions were used to determine the concentrations of NH 4 + , sodium (Na + ), potassium (K + ), magnesium (Mg 2+ ) and calcium (Ca 2+ (Kirkby & Mengel 1967), as appropriate concentrations of these ions are required to maintain the stability and function of enzymes and cell membranes (Davenport et al 1997, Wei et al 2003.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, plant cell membrane permeability is sensitive to external ion concentrations and closely associated with ion flux between the plant and its environment (Llamas et al 2000, Suwalsky et al 2009). High NH 4 + concentrations are reported to affect the growth and mineral composition of submersed macrophytes (Kirkby & Mengel 1967, Vale et al 1987, 1988, Gerendas et al 1997, Gloser & Gloser 2000, but the underlying mechanisms of NH 4 + toxicity are far from clear, especially due to the lack of data concerning possible changes in membrane permeability under NH 4 + stress. Myriophyllum spicatum and Ceratophyllum demersum are submersed macrophytes dwelling in eutrophic waters worldwide (Nichols & Shaw 1986, Royer & Minshall 1997.…”

Section: Introductionmentioning

confidence: 99%

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