Regulation of NH4 + uptake in wheat plants: Effect of root ammonium concentration and amino acids

Causin, Humberto F.; Barneix, Atilio J.

doi:10.1007/bf00016286

Cited by 42 publications

(22 citation statements)

References 31 publications

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“…Possible indicators are foliar N analysis and ratios of other elements to N (Cape et al, 1990 ;Bauer et al, 1997 ;Aber et al, 1998). Although total leaf N status is an indicator of plant N demand, it does not always predict plant capacity to absorb additional N. Rather, root capacity to absorb NO $ − and NH % + is more closely associated with specific pools of N, for example, root cytoplasmic concentration of NO $ − , NH % + , or specific amino acids such as glutamine and aspargine (Lee & Drew, 1986 ;Siddiqi et al, 1990 ;Cousin & Barneix, 1993). In addition, interpretation of foliar N can be confounded if NO # − and NH $ deposition intercepted and absorbed by the leaf is translocated to the root where it elicits a feedback inhibition of uptake (Rennenberg & Gessler, 1999).…”

Section: Responses To N Depositionmentioning

confidence: 99%

Kinetics of nutrient uptake by roots: responses to global change

2000

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There is a growing recognition that accurate predictions of plant and ecosystem responses to global change require a better understanding of the mechanisms that control acquisition of growth-limiting resources. One such key mechanism is root physiological capacity to acquire nutrients. Changes in kinetics of root nitrogen (N) uptake might influence the extent to which terrestrial ecosystems will be able to sequester excesses in carbon (C) and N loads. Despite its significant role in determining plant and ecosystem cycling of C and N, there is little information on whether, or how, root nutrient uptake responds to global change. In this review various components of global change, namely increased CO # concentration, increased soil temperature and increased atmospheric N deposition and their effects on kinetics of root nutrient uptake are examined. The response of root nutrient uptake kinetics to high CO # is highly variable. Most of this variability might be attributable to differences in experimental protocols, but more recent evidence suggests that kinetic responses to high CO # are also species-specific. This raises the possibility that elevated CO # might alter community composition by shifting the competitive interaction of co-occurring species. Uptake of NH % + and NO $ − seem to be differentially sensitive to high CO # , which could influence ecosystem trajectory toward N saturation. Increased soil temperature might increase N and P uptake capacity to a greater extent in species from warm and fluctuating soil habitats than in species from cold and stable soil environments. The few available data also indicate that increased soil temperature elicits a differential effect on uptake of NH % + versus NO $ − . Root uptake kinetics are generally down-regulated in response to long-term exposure to atmospheric N deposition. The extent of this down-regulation might, however, vary among species, stages of succession, land-use history and plant demand. Nonetheless, it is suggested that root N uptake kinetics might be an accurate biological indicator of the ecosystem capacity to retain N. The results reviewed here clearly highlight the scanty nature of the literature in the area of root nutrient absorption responses to global change. It is also clear that effects of one component of global change on root nutrient absorption capacity might be counterbalanced by another. Therefore, the generalizations offered here must be viewed with caution and more effort should be directed to rigorously test these initial observations in future research.

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Section: Responses To N Depositionmentioning

confidence: 99%

Kinetics of nutrient uptake by roots: responses to global change

2000

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“…Nitrate and NH 4 are the most abundant N sources for higher plants, and their availability usually constitutes a limiting factor for plant growth (Causin and Barneix, 1993). The individual physiological responses of plants to these N sources are quite different as is their ability to absorb and assimilate them (Lewis et al, 1982;Pilbeam and Kirkby, 1992;Botella et al, 1994a).…”

Section: Introductionmentioning

confidence: 99%

Effect of salinity on the growth and nitrogen uptake by wheat seedlings

Botella

Martı́nez

Nieves

et al. 1997

Journal of Plant Nutrition

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Saline conditions affect nitrogen (N) assimilation of higher plants. To study the effect of salinity and N source on growth and N uptake in wheat (Triticum aestivum L.), plants were grown in a growth chamber under controlled conditions. The nutrient solution contained 4 mM N, applied as either calcium nitrate [Ca(NO 3 ) 2 ] or ammonium sulfate [(NH 4 ) 2 SO 4 ], or a mixture of both, and the salinity treatments consisted in two levels of sodium chloride (NaCl) (1 and 60 mM). Salinity significantly reduced shoot and root growth and the effect of the N source was dependent on which salinity treatment was applied. Salinity decreased the net uptake rate of nitrate (NO 3 ) and NO 3 +ammonium (NH 4 ), but had little effect on NH 4 uptake when this nutrient was applied alone. Dark conditions affected NO 3 uptake to a greater extent than NH 4 uptake. The best N source for wheat growth was a mixture of NO 3 and NH 4 , especially under saline conditions or periods of low irradiance. 793

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“…Previous studies have shown that nitrogen regimes and sources influenced greatly on the concentration of free amino acids in the leaves and roots of plant species (Haynes and Goh, 1978;Darral and Wareing, 1981;Barneix et al, 1984). Nitrogen-deficient plants showed faster nitrate (Lee and Rudge, 1986;Rodgers and Barneix, 1989;Rufty et al, 1990) and ammonium (Morgan and Jackson, 1988a;Causin and Barneix, 1993) uptake rates than nitrogen-fed plants to sustain the levels of free amino acids in organs, and also ammonium uptake of plants were conversely enhanced against nitrate deficiency (Sung et al, 2011). Free amino acid concentration in both leaves and roots under nitrogen deficiency remained low while it showed similar level in nitrogen-normal and -surplus conditions (Table 1).…”

Section: Discussionmentioning

confidence: 99%

Temporal Changes in N Assimilation and Metabolite Composition of Nitrate-Affected Tomato Plants

Sung¹,

Lee²,

Lee³

et al. 2012

Korean Journal of Soil Science and Fertilizer

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The role of inorganic nitrogen assimilation in the production of amino acids, organic acids and soluble sugars is one of the most important biochemical processes in plants, and, in order to achieve normally, nitrate uptake and assimilation is essential. For this reason, the characterization of nitrate assimilation and metabolite composition from leaves, roots and xylem sap of tomato (Solanum lycopersicum) was investigated under different nitrate levels in media. Tomato plants were grown hydroponically in liquid culture under five different nitrate regimes: deficient (0.25 and 0.75 mM NO 3 -), normal (2.5 mM NO 3 -) and excessive (5.0 and 10.0 mM NO 3 -). All samples, leaves, roots and xylem sap, were collected after 7 and 14 days after treatment. The levels of amino acids, soluble sugars and organic acids were significantly decreased by N-deficiency whereas, interestingly, they remained higher in xylem sap as compared with N-normal and -surplus. The N-excessive condition did not exert any significant changes in metabolites composition, and thus their levels were similar with N-normal. The gene expression and enzyme activity of nitrate reductase (NR), nitrite reductase (NIR) and glutamine synthetase (GS) were greatly influenced by nitrate. The data presented here suggest that metabolites, as a signal messenger, existed in xylem sap seem to play a crucial role to acquire nitrate, and, in addition, an increase in α-ketoglutarate pathway-derived amino acids under N-deficiency may help to better understand plant C/N metabolism.

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Regulation of NH4 + uptake in wheat plants: Effect of root ammonium concentration and amino acids

Cited by 42 publications

References 31 publications

Kinetics of nutrient uptake by roots: responses to global change

Kinetics of nutrient uptake by roots: responses to global change

Effect of salinity on the growth and nitrogen uptake by wheat seedlings

Temporal Changes in N Assimilation and Metabolite Composition of Nitrate-Affected Tomato Plants

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