Root Nitrogen Acquisition and Assimilation

Miller, Anthony J.; Cramer, Michael D.

doi:10.1007/s11104-004-0965-1

Cited by 549 publications

(232 citation statements)

References 305 publications

(292 reference statements)

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“…Soil amino acid concentrations are also commonly low, relative to [NO 3 − ] and [NH 4 + ], resulting in limited access of plant roots to these N-forms (Jones et al, 2005) and limited potential for fractionation. Nutrient uptake mechanisms allow roots to take up N at low concentrations and consequently deplete soil N to low concentrations (Miller and Cramer 2005), which is consistent with the fact that observed fractionation is especially small when soil [N] are low (Evans 2001;Evans et al 1996;McKee et al 2002;Montoya and McCarthy 1995). It is only when soil [N] is high that significant fractionation may be common.…”

Section: Nitrogen Uptakesupporting

confidence: 82%

“…In warmer ecosystems, either NH 4 + or NO 3 − may dominate the inorganic N pool of an ecosystem (Kronzucker et al 1997). Although plants benefit energetically from taking up the most reduced form of N, excessive uptake of NH 4 + can be toxic (Miller and Cramer 2005) and plant N uptake preferences track the availability of different forms of N across different environmental conditions (Wang and Macko 2011). Losses of bioavailable N can be indicative of the N limitation status of plants and microbes and tend to increase with increasing external inputs and availability (e.g., Brookshire et al 2012a;Vitousek et al 1989;Wang et al 2007).…”

Section: Background On the N Cycle And N Isotopesmentioning

confidence: 99%

“…Both NO 3 − and NH 4 + efflux are thought to function for regulation of cytoplasmic N concentrations. This might be especially important for NH 4 + (Britto and Kronzucker 2002), which can be toxic when supplied at high concentrations (Miller and Cramer 2005). Apart from efflux of inorganic N, root exudation of amino acids also occurs (Farrar et al 2003), resulting in the loss of 15 N-depleted organic N from the roots.…”

Section: Nitrogen Uptakementioning

confidence: 99%

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Ecological interpretations of nitrogen isotope ratios of terrestrial plants and soils

et al. 2015

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Background Knowledge of biological and climatic controls in terrestrial nitrogen (N) cycling within and across ecosystems is central to understanding global patterns of key ecosystem processes. The ratios of 15 N: 14 N in plants and soils have been used as indirect indices of N cycling parameters, yet our understanding of controls over N isotope ratios in plants and soils is still developing. Scope In this review, we provide background on the main processes that affect plant and soil N isotope ratios. In a similar manner to partitioning the roles of state factors and interactive controls in determining ecosystem traits, we review N isotopes patterns in plants and soils across a number of proximal factors that influence ecosystem properties as well as mechanisms that affect these patterns. Lastly, some remaining questions that would improve our understanding of N isotopes in terrestrial ecosystems are highlighted. Conclusion Compared to a decade ago, the global patterns of plant and soil N isotope ratios are more resolved. Additionally, we better understand how plant and soil N isotope ratios are affected by such factors as mycorrhizal fungi, climate, and microbial processing. A comprehensive understanding of the N cycle that ascribes different degrees of isotopic fractionation for each step under different conditions is closer to being realized, but a number of process-level questions still remain.

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Section: Nitrogen Uptakesupporting

confidence: 82%

Section: Background On the N Cycle And N Isotopesmentioning

confidence: 99%

Section: Nitrogen Uptakementioning

confidence: 99%

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Ecological interpretations of nitrogen isotope ratios of terrestrial plants and soils

et al. 2015

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“…For their different N utilization strategies and aboveground biomass proportions, plants in alpine meadows can be divided into two functional groups, vascular plants and bryophytes. The former is best known as assimilating nutrient primarily from soil with developed root systems (Chapin 1980;vonWiren et al 1997;Miller and Cramer 2005), while the latter is thought to access its major nutrient source from atmospheric deposition due to lack of developed root and vascular systems (Vantooren et al 1990; Ayres et al 2006). Although bryophytes generally appear to rely mainly on atmospheric deposition, the previous research of Polytrichum alpinum and Racomitrium lanuginosum through 15 N tracer applications demonstrated that bryophytes can directly derive N from the soil (Ayres et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Uptake and recovery of soil nitrogen by bryophytes and vascular plants in an alpine meadow

Wang

Shi

et al. 2014

J. Mt. Sci.

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Due to their particular physiology and life history traits, bryophytes are critical in regulating biogeochemical cycles and functions in alpine ecosystem. Hence, it is crucial to investigate their nutrient utilization strategies in comparison with vascular plants and understand their responses to the variation of growing season caused by climate change. Firstly, this study testified whether or not bryophytes can absorb nitrogen (N) directly from soil through spiking three chemical forms of 15N stable isotope tracer.Secondly, with stronger ability of carbohydrates assimilation and photosynthesis, it is supposed that N utilization efficiency of vascular plants is significantly higher than that of bryophytes. However, the recovery of soil N by bryophytes can still compete with vascular plants due to their greater phytomass. Thirdly, resource acquisition may be varied from the change of growing season, during which N pulse can be manipulated with 15N tracer addition at different time. Both of bryophytes and vascular plants contain more N in a longer growing season, and prefer inorganic over organic N. Bryophytes assimilate more NH4+ than NO3-and amino acid, which can be indicated from the greater shoot excess 15N of bryophytes. However, vascular plants prefer to absorb NO3-for their developed root systems and vascular tissue. Concerning the uptake of three forms N by bryophytes, there is significant difference between two manipulated lengths of growing season. Furthermore, the capacity of bryophytes to tolerate N-pollution may be lower than currently appreciated, which indicates the effect of climate change on asynchronous variation of soil N pools with plant requirements.

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“…The soil ammonium and nitrate concentration ranges from micro molar levels to hundreds of milli molar quantities [1] [30]. The diffusion coefficient of nitrate in soil is the consequence of nitrate available to plant roots and the nitrate lost through leaching (about 30% of inorganic nitrogen) [31] [32].…”

Section: Nitrogen In Soilmentioning

confidence: 99%

Nitrogen Nutrition, Its Regulation and Biotechnological Approaches to Improve Crop Productivity

Reddy¹,

Ulaganathan²

2015

AJPS

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Nitrogen is the most important macronutrient needed for plant growth and development. The availability of nitrogen in the soil fluctuates greatly in both time and space. Crop plants, except leguminous plants, depend on supply of nitrogen as fertilizers. Large quantities of nitrogen fertilizers are applied to crop plants, but only 33% of it is utilized by the plant. Plants have developed efficient mechanisms to sense the varying levels of nitrogen forms and uptake them. They also have well developed mechanisms to assimilate the incoming nitrogen immediately or translocate to different parts of the plant wherever it is needed. Maintenance of nitrogen homeostasis is essential to avoid toxicity. Apart from translocation and assimilation, plants have developed different mechanisms, nitrogen efflux; vacuolar nitrogen storage and downward transport of nitrogen from aerial parts to roots, for maintaining nitrogen homeostasis. In crop plants the "grain yield per unit of available nitrogen in the soil" is referred as the nitrogen use efficiency (NUE) for which remobilization of nitrogen, mediated by various transporters plays a crucial role. All these processes are tightly regulated by proteins and microRNA in response to both external and internal nitrogen levels, carbon status of the plant and hormones. As most crop plants are non-leguminous and depend on soil nitrogen, more production could be achieved if crop plants can be made to utilize the available nitrogen efficiently. The recent explosion of research information and the mechanisms behind nitrogen sensing, signaling, transport and utilization enables biotechnological interventions for better nitrogen nutrition of crop plants. This review discusses such possibilities in the context of recent understanding of nitrogen nutrition and the genomic revolution sweeping the crop science.

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Root Nitrogen Acquisition and Assimilation

Cited by 549 publications

References 305 publications

Ecological interpretations of nitrogen isotope ratios of terrestrial plants and soils

Ecological interpretations of nitrogen isotope ratios of terrestrial plants and soils

Uptake and recovery of soil nitrogen by bryophytes and vascular plants in an alpine meadow

Nitrogen Nutrition, Its Regulation and Biotechnological Approaches to Improve Crop Productivity

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