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Nicola Tomasi - One of the best experts on this subject based on the ideXlab platform.
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influence of different trap solutions on the determination of root exudates in lupinus albus l
Biology and Fertility of Soils, 2015Co-Authors: Fabio Valentinuzzi, Nicola Tomasi, Stefano Cesco, Tanja MimmoAbstract:White lupin is very often used as a model plant for root Exudation studies due to its capability to release huge amounts of organic acids and flavonoids. The complex nature of these organic compounds makes not only their analytical determination difficult but also their extraction from soil samples. For these reasons simplified approaches, as hydroponic-based systems are widely used to study the root Exudation. Therefore, the composition of a trap solution is crucial to limit artefacts causing over/underestimation of Exudation rates and/or a biased molecular composition of the collected compounds. The present study was aimed at assessing the influence of different trap solutions and collection times on the quali- and quantitative root Exudation pattern of white lupin (Lupinus albus L.) grown under phosphorus (P) and iron (Fe) deficiency. Our results suggest that, in works aimed at studying root Exudation processes, water is the most effective trap solution to collect the exudates like organic acids and flavonoids, especially in short time (e.g. 2 h). For longer times, low concentrations of Ca could be helpful to limit osmotic stress and possible passive leakage and/or diffusion. The use of bacteriostatic compounds as NaN3 and Micropur bias the results, due to interferences either with the metabolism or inhibition of the Exudation processes, especially in the case of flavonoids such as quercetin. Also, the use of a pH buffer solution like 2-(N-morpholino)ethanesulfonic acid (MES) should be avoided for its undesired interferences with the release.
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plasma membrane h atpase dependent citrate Exudation from cluster roots of phosphate deficient white lupin
Plant Cell and Environment, 2009Co-Authors: Nicola Tomasi, Tobias Kretzschmar, L Espen, Laure Weisskopf, Anja T Fuglsang, Michael G Palmgren, Gunter Neumann, Zeno Varanini, R PintonAbstract:White lupin (Lupinus albus L.) is able to grow on soils with sparingly available phosphate (P) by producing specialized structures called cluster roots. To mobilize sparingly soluble P forms in soils, cluster roots release substantial amounts of carboxylates and concomitantly acidify the rhizosphere. The relationship between acidification and carboxylate Exudation is still largely unknown. In the present work, we studied the linkage between organic acids (malate and citrate) and proton Exudations in cluster roots of P-deficient white lupin. After the illumination started, citrate Exudation increased transiently and reached a maximum after 5 h. This effect was accompanied by a strong acidification of the external medium and alkalinization of the cytosol, as evidenced by in vivo nuclear magnetic resonance (NMR) analysis. Fusicoccin, an activator of the plasma membrane (PM) H+-ATPase, stimulated citrate Exudation, whereas vanadate, an inhibitor of the H+-ATPase, reduced citrate Exudation. The burst of citrate Exudation was associated with an increase in expression of the LHA1 PM H+-ATPase gene, an increased amount of H+-ATPase protein, a shift in pH optimum of the enzyme and post-translational modification of an H+-ATPase protein involving binding of activating 14-3-3 protein. Taken together, our results indicate a close link in cluster roots of P-deficient white lupin between the burst of citrate Exudation and PM H+-ATPase-catalysed proton efflux.
Jianbo Shen - One of the best experts on this subject based on the ideXlab platform.
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interactions between light intensity and phosphorus nutrition affect the phosphate mining capacity of white lupin lupinus albus l
Journal of Experimental Botany, 2014Co-Authors: Lingyun Cheng, Xiaoyan Tang, Carroll P Vance, Philip J White, F Zhang, Jianbo ShenAbstract:Light intensity affects photosynthetic carbon (C) fixation and the supply of carbon to roots. To evaluate interactions between carbon supply and phosphorus (P) supply, effects of light intensity on sucrose accumulation, root growth, cluster root formation, carboxylate Exudation, and P uptake capacity were studied in white lupin (Lupinus albus L.) grown hydroponically with either 200 µmol m –2 s –1 or 600 µmol m –2 s –1 light and a sufficient (50 µM P) or deficient (1 µM P) P supply. Plant biomass and root:shoot ratio increased with increasing light intensity, particularly when plants were supplied with sufficient P. Both low P supply and increasing light intensity increased the production of cluster roots and citrate Exudation. Transcripts of a phosphoenol pyruvate carboxylase gene (LaPEPC3) in cluster roots (which is related to the Exudation of citrate), transcripts of a phosphate transporter gene (LaPT1), and P uptake all increased with increasing light intensity, under both P-sufficient and P-deficient conditions. Across all four experimental treatments, increased cluster root formation and carboxylate Exudation were associated with lower P concentration in the shoot and greater sucrose concentration in the roots. It is suggested that C in excess of shoot growth capabilities is translocated to the roots as sucrose, which serves as both a nutritional signal and a C-substrate for carboxylate Exudation and cluster root formation.
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citrate Exudation from white lupin induced by phosphorus deficiency differs from that induced by aluminum
New Phytologist, 2007Co-Authors: Baolan Wang, Jianbo Shen, Wengen Zhang, Fusuo Zhang, Gunter NeumannAbstract:Summary • Both phosphorus (P) deficiency and aluminum (Al) toxicity induce root Exudation of carboxylates, but the relationship between these two effects is not fully understood. Here, carboxylate Exudation induced by Al in Lupinus albus (white lupin) was characterized and compared with that induced by P deficiency. • Aluminum treatments were applied to whole root systems or selected root zones of plants with limited (1 µ M ) or sufficient (50 µ M ) P supply. • Aluminum stimulated citrate efflux after 1‐2 h; this response was not mimicked by a similar trivalent cation, La 3 + . P deficiency triggered citrate release from mature cluster roots, whereas Al stimulated citrate Exudation from the 5- to 10-mm subapical root zones of lateral roots and from mature and senescent cluster roots. Al-induced citrate Exudation was inhibited by P limitation at the seedling stage, but was stimulated at later growth stages. Citrate Exudation was sensitive to anion-channel blockers. Al treatments did not affect primary root elongation, but inhibited the elongation of lateral roots. • The data demonstrate differential patterns of citrate Exudation in L. albus , depending on root zone, developmental stage, P nutritional status and Al stress. These findings are discussed in terms of possible functions and underlying mechanisms.
Gunter Neumann - One of the best experts on this subject based on the ideXlab platform.
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plasma membrane h atpase dependent citrate Exudation from cluster roots of phosphate deficient white lupin
Plant Cell and Environment, 2009Co-Authors: Nicola Tomasi, Tobias Kretzschmar, L Espen, Laure Weisskopf, Anja T Fuglsang, Michael G Palmgren, Gunter Neumann, Zeno Varanini, R PintonAbstract:White lupin (Lupinus albus L.) is able to grow on soils with sparingly available phosphate (P) by producing specialized structures called cluster roots. To mobilize sparingly soluble P forms in soils, cluster roots release substantial amounts of carboxylates and concomitantly acidify the rhizosphere. The relationship between acidification and carboxylate Exudation is still largely unknown. In the present work, we studied the linkage between organic acids (malate and citrate) and proton Exudations in cluster roots of P-deficient white lupin. After the illumination started, citrate Exudation increased transiently and reached a maximum after 5 h. This effect was accompanied by a strong acidification of the external medium and alkalinization of the cytosol, as evidenced by in vivo nuclear magnetic resonance (NMR) analysis. Fusicoccin, an activator of the plasma membrane (PM) H+-ATPase, stimulated citrate Exudation, whereas vanadate, an inhibitor of the H+-ATPase, reduced citrate Exudation. The burst of citrate Exudation was associated with an increase in expression of the LHA1 PM H+-ATPase gene, an increased amount of H+-ATPase protein, a shift in pH optimum of the enzyme and post-translational modification of an H+-ATPase protein involving binding of activating 14-3-3 protein. Taken together, our results indicate a close link in cluster roots of P-deficient white lupin between the burst of citrate Exudation and PM H+-ATPase-catalysed proton efflux.
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citrate Exudation from white lupin induced by phosphorus deficiency differs from that induced by aluminum
New Phytologist, 2007Co-Authors: Baolan Wang, Jianbo Shen, Wengen Zhang, Fusuo Zhang, Gunter NeumannAbstract:Summary • Both phosphorus (P) deficiency and aluminum (Al) toxicity induce root Exudation of carboxylates, but the relationship between these two effects is not fully understood. Here, carboxylate Exudation induced by Al in Lupinus albus (white lupin) was characterized and compared with that induced by P deficiency. • Aluminum treatments were applied to whole root systems or selected root zones of plants with limited (1 µ M ) or sufficient (50 µ M ) P supply. • Aluminum stimulated citrate efflux after 1‐2 h; this response was not mimicked by a similar trivalent cation, La 3 + . P deficiency triggered citrate release from mature cluster roots, whereas Al stimulated citrate Exudation from the 5- to 10-mm subapical root zones of lateral roots and from mature and senescent cluster roots. Al-induced citrate Exudation was inhibited by P limitation at the seedling stage, but was stimulated at later growth stages. Citrate Exudation was sensitive to anion-channel blockers. Al treatments did not affect primary root elongation, but inhibited the elongation of lateral roots. • The data demonstrate differential patterns of citrate Exudation in L. albus , depending on root zone, developmental stage, P nutritional status and Al stress. These findings are discussed in terms of possible functions and underlying mechanisms.
Steffen Abel - One of the best experts on this subject based on the ideXlab platform.
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arabidopsis transporter abcg37 pdr9 contributes primarily highly oxygenated coumarins to root Exudation
Scientific Reports, 2017Co-Authors: Jorg Ziegler, Stephan Schmidt, Nadine Strehmel, Dierk Scheel, Steffen AbelAbstract:The chemical composition of root exudates strongly impacts the interactions of plants with microorganisms in the rhizosphere and the efficiency of nutrient acquisition. Exudation of metabolites is in part mediated by ATP-binding cassette (ABC) transporters. In order to assess the contribution of individual ABC transporters to root Exudation, we performed an LC-MS based non-targeted metabolite profiling of semi-polar metabolites accumulating in root exudates of Arabidopsis thaliana plants and mutants deficient in the expression of ABCG36 (PDR8/PEN3), ABCG37 (PDR9) or both transporters. Comparison of the metabolite profiles indicated distinct roles for each ABC transporter in root Exudation. Thymidine Exudation could be attributed to ABCG36 function, whereas coumarin Exudation was strongly reduced only in ABCG37 deficient plants. However, coumarin Exudation was compromised in abcg37 mutants only with respect to certain metabolites of this substance class. The specificity of ABCG37 for individual coumarins was further verified by a targeted LC-MS based coumarin profiling method. The response to iron deficiency, which is known to strongly induce coumarin Exudation, was also investigated. In either treatment, the distribution of individual coumarins between roots and exudates in the investigated genotypes suggested the involvement of ABCG37 in the Exudation specifically of highly oxygenated rather than monohydroxylated coumarins.
Hans Lambers - One of the best experts on this subject based on the ideXlab platform.
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inoculation with azospirillum brasilense ab v4 ab v5 increases zea mays root carboxylate Exudation rates dependent on soil phosphorus supply
Plant and Soil, 2017Co-Authors: Andre Mouro Dangioli, Ricardo Augusto Gorne Viani, Hans Lambers, Alexandra Christine Helena Frankland Sawaya, Rafael S OliveiraAbstract:We aimed to investigate the effects of root carboxylate Exudation in the interaction between Azospirillum brasilense and Zea mays. We hypothesized that root carboxylate Exudation is a mechanism that increases colonization of the maize rhizosphere by A. brasilense and that carboxylate Exudation would increase at a low soil phosphorus (P) availability. We conducted a greenhouse experiment, using maize seeds inoculated and uninoculated with A. brasiliense. Seeds were planted in pots, supplied with nutrient solution, varying in P concentration. After 45 days we measured total plant biomass, root length and area, plant nutrient status, and the root carboxylate-Exudation rate. Inoculation increased the root length and area, and this effect increased with increasing P supply. Inoculated plants also showed an increased root carboxylate-Exudation rate. For inoculated treatments, the Exudation rate was positively correlated with root architecture parameters; however, it was negatively correlated with leaf manganese concentration, a proxy for the amount of carboxylates in the rhizosphere. Inoculation of A. brasilense stimulated root carboxylate Exudation, which was positively correlated with root length and area. These positive correlations are probably mediated by the effect of carboxylates on the rhizosphere microbial community. This indicates a positive feedback in which A. brasilense inoculation stimulates root carboxylate Exudation, influencing the rhizosphere microbial community. It results in positive effects on maize root architecture. The root length of inoculated plants was positively correlated with P supply, indicating that P supply positively affects the microbial community, modulating the interaction between A. brasilense and Z. mays.
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shoot p status regulates cluster root growth and citrate Exudation in lupinus albus grown with a divided root system
Plant Cell and Environment, 2003Co-Authors: Michael W Shane, S De Roock, Hans LambersAbstract:The present study was carried out to investigate whether the P concentration in the roots or the shoots controls the growth and citrate Exudation of cluster roots in white lupin ( Lupinus albus L). Foliar P application indicated that low P concentration in the shoots enhanced cluster-root growth and citrate-Exudation rate more so than low P concentration in the roots. In the split-root study, the P concentration in the shoots increased with increased P supply (1, 25 or 75 mmol m - 3 P), to the ‘privileged’ root halves. Roots ‘deprived’ of P invariably had the same low P concentrations, whereas those in the ‘privileged’ roots increased with increasing P supply (1, 25 or 75 mmol m - 3 P). Nevertheless, the proportion of the total root mass allocated to cluster roots, and the citrate-Exudation rates from the root halves were always similar on both root halves, irrespective of P supply, and decreased with increasing shoot P concentrations. Peak citrate Exudation rates from developing cluster roots were significantly faster from cluster roots on the ‘deprived’ root halves when the ‘privileged’ half was exposed to 1 mmol m - 3 P as compared with 25 or - 3 P. The possibility that changes in the concentrations of P fractions in the root halves influenced clusterroot growth and citrate Exudation was discounted, because there were no significant differences in insoluble organic P, ester-P and inorganic P among all ‘deprived’ root halves. The results indicate that cluster-root proportions and citrate Exudation rates were regulated systemically by the P status of the shoot, and that P concentrations in the roots had little influence on growth and citrate Exudation of cluster roots in L. albus .
