Role of proteinaceous amino acids released in root exudates in nutrient acquisition from the rhizosphere

Jones, Davey L.; Edwards, Anthony C.; Donachie, K.; Darrah, P. R.

doi:10.1007/bf00009493

Cited by 91 publications

(22 citation statements)

References 28 publications

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“…Based on studies on the permeability of lipid bilayers to polar substances, Jones et al (1994) reported a release of amino acids from plant roots by passive diusion at a rate of approximately 0.27 nmol h A1 (cm root length) A1 . This is in agreement with citric acid exudation of 0.1± 0.2 n mol h A1 (cm root length) A1 measured for 5-mm tip segments of non-proteoid roots in the present study.…”

Section: Discussionmentioning

confidence: 99%

Physiological adaptations to phosphorus deficiency during proteoid root development in white lupin

Neumann

Massonneau

Martinoia

et al. 1999

Planta

394

242

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Release of large amounts of citric acid from specialized root clusters (proteoid roots) of phosphorus (P)-de®cient white lupin (Lupinus albus L.) is an ecient strategy for chemical mobilization of sparingly available P sources in the rhizosphere. The present study demonstrates that increased accumulation and exudation of citric acid and a concomitant release of protons were predominantly restricted to mature root clusters in the later stages of P de®ciency. Inhibition of citrate exudation by exogenous application of anion-channel blockers such as ethacrynic-and anthracene-9-carboxylic acids may indicate involvement of an anion channel. Phosphorus-de®ciency-induced accumulation and subsequent exudation of citric acid seem to be a consequence of both increased biosynthesis and reduced metabolization of citric acid in the proteoid root tissue, indicated by increased in-vitro activity and enzyme protein levels of phosphoenolpyruvate carboxylase (EC 4.1.1.31), and reduced activity of aconitase (EC 4.2.1.3) and root respiration. Similar to citric acid, acid phosphatase, which is secreted by roots and involved in the mobilization of the organic soil P fraction, was released predominantly from proteoid roots of P-de®cient plants. Also 33 Pi uptake per unit root fresh-weight was increased by approximately 50% in juvenile and mature proteoid root clusters compared to apical segments of non-proteoid roots. Kinetic studies revealed a K m of 30.7 lM for Pi uptake of non-proteoid root apices in P-sucient plants, versus K m values of 8.5±8.6 lM for non-proteoid and juvenile proteoid roots under P-de®cient conditions, suggesting the induction of a high-anity Pi-uptake system. Obviously, P-de®ciency-induced adaptations of white lupin, involved in P acquisition and mobilization of sparingly available P sources, are predominantly con®ned to proteoid roots, and moreover to distinct stages during proteoid root development.Dedicated to the memory of Prof. Horst Marschner, who initiated this cooperation project Abbreviations: APase = acid phosphatase; P = phosphorus; Pi = inorganic phosphate; PEPC = phosphoenolpyruvate carboxylase

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Section: Discussionmentioning

confidence: 99%

Physiological adaptations to phosphorus deficiency during proteoid root development in white lupin

Neumann

Massonneau

Martinoia

et al. 1999

Planta

394

242

View full text Add to dashboard Cite

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“…However, rhizodeposition (Whipps, 1990;Merbach, et al 1999), including root exudates of C and N compounds (Jaeger et al, 1999), and higher microbial and microfaunal populations affect N cycling in the rhizosphere (Griffiths, 1994;Bonkowski et al, 2000). Under the influence of live roots, N-turnover may be faster than in soil without plants (Clarholm, 1985;Jones et al, 1994).…”

Section: Introductionmentioning

confidence: 97%

Plant and microbial nitrogen use and turnover: Rapid conversion of nitrate to ammonium in soil with roots

Burger

Jackson

2005

Plant Soil

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Immobilization of ammonium (NH + 4 ) by plants and microbes, a controlling factor of ecosystem nitrogen (N) retention, has usually been measured based on uptake of 15 NH + 4 solutions injected into soil. To study the influence of roots on N dynamics without stimulating consumption of NH + 4 , we estimated gross nitrification in the presence or absence of live roots in an agricultural soil. Tomato (Lycopersicon esculentum var. Peto76) plants were grown in microcosms containing root exclosures. When the plants were 7 weeks old, 15 N enriched nitrate (NO − 3 ) was applied in the 0-150 mm soil layer. After 24 h, > 30 times more 15 NH + 4 was found in the soil with roots than in the soil of the root exclosures. At least 18% of the NH + 4 -N present at this time in the soil with roots had been converted from NO − 3 . We estimated rates of conversion of NO − 3 to NH + 4 , and rates of NH + 4 immobilization by plants and microbes, by simulating N-flow of 14+15 N and 15 N in three models representing mechanisms that may be underlying the experimental data: Dissimilatory NO − 3 reduction to NH + 4 (DNRA), plant N efflux, and microbial biomass nitrogen (MBN) turnover. Compared to NO − 3 uptake, plant NH + 4 uptake was modest. Ammonium immobilization by plants and microbes was equal to at least 35% of nitrification rates. The rapid recycling of NO − 3 to NH + 4 via plants and/or microbes contributes to ecosystem N retention and may enable plants growing in agricultural soils to capture more NH + 4 than generally assumed.

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“…Most plants are capable of exudating some low molecular weight organic acids (LMWOAs), such as citric, malic, oxalic, and succinic acids (Dakora and Phillips, 2002). These organic acids can react with metal ions in both the soil solution and solid phases (Jones et al, 1994;Nigam et al, 2000), and increase metal mobility in the rhizospheric environment, thereby improving the phytoavailability of metals to plants (Lopez-Bucio et al, 2000;Ma et al, 2001). Enhancement of cadmium (Cd) solubility by various organic acids in soils and subsequent metal uptake by plants has been widely reported (Nigam et al, 2000;Han et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Improved cadmium uptake and accumulation in the hyperaccumulator Sedum alfredii: the impact of citric acid and tartaric acid

Tian

Yang

et al. 2013

J. Zhejiang Univ. Sci. B

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Abstract:The elucidation of a natural strategy for metal hyperaccumulation enables the rational design of technologies for the clean-up of metal-contaminated soils. Organic acid has been suggested to be involved in toxic metallic element tolerance, translocation, and accumulation in plants. The impact of exogenous organic acids on cadmium (Cd) uptake and translocation in the zinc (Zn)/Cd co-hyperaccumulator Sedum alfredii was investigated in the present study. By the addition of organic acids, short-term (2 h) root uptake of 109 Cd increased significantly, and higher 109 Cd contents in roots and shoots were noted 24 h after uptake, when compared to controls. About 85% of the 109 Cd taken up was distributed to the shoots in plants with citric acid (CA) treatments, as compared with 75% within controls. No such effect was observed for tartaric acid (TA). Reduced growth under Cd stress was significantly alleviated by low CA. Long-term application of the two organic acids both resulted in elevated Cd in plants, but the effects varied with exposure time and levels. The results imply that CA may be involved in the processes of Cd uptake, translocation and tolerance in S. alfredii, whereas the impact of TA is mainly on the root uptake of Cd.

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Role of proteinaceous amino acids released in root exudates in nutrient acquisition from the rhizosphere

Cited by 91 publications

References 28 publications

Physiological adaptations to phosphorus deficiency during proteoid root development in white lupin

Physiological adaptations to phosphorus deficiency during proteoid root development in white lupin

Plant and microbial nitrogen use and turnover: Rapid conversion of nitrate to ammonium in soil with roots

Improved cadmium uptake and accumulation in the hyperaccumulator Sedum alfredii: the impact of citric acid and tartaric acid

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