In this issue, Schenkeveld and coworkers described the potential of phytosiderophores (a class of root exudates) to mobilize metals in the rhizosphere by an equilibrium modelling approach.
The rhizosphere is a complex and dynamic environment where several different organic and inorganic compounds coexist. Due to the different concentration and chemical characteristics there might be competitive and synergistic interactions. However the rhizosphere is strongly influenced by root activity: water and nutrient uptake, root respiration that might modify the pH and redox status of the rhizosphere. Thus, how does the complexity of the system and the dynamics influence the thermodynamics of the single process? Can chemical equilibria be really reached in the rhizosphere? Issues related to kinetics vs thermodynamics are discussed. The study of the single processes is important but more complex researches, being thus more realistic (i.e. field-like conditions), are necessary. Hence, what are the available tools/methods in rhizosphere research? What are the drawbacks? How can the results of these methods be related to thermodynamic and kinetic models?
Besides stimulating further awareness around the rhizosphere complexity, tentative answers are given highlighting the future challenges in rhizosphere research, essential knowledge for the development of agronomic practices ensuring a better exploitation of soil endogenous resources of nutrients by crops.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Tax calculation will be finalised during checkout.
Bais HP, Park SW, Weir TL, Callaway RM, Vivanco JM (2004) How plants communicate using the underground information superhighway. Trends Plant Sci 9:26–32
Blossfeld S (2013) Light for the dark side of plant life: − Planar optodes visualizing rhizosphere processes. Plant Soil 369(1–2):29–32
Blossfeld S, Schreiber CM, Liebsch G, Kuhn AJ, Hinsinger P (2013) Quantitative imaging of rhizosphere pH and CO2 dynamics with planar optodes. Ann Bot 112(2):267–276
Cesco S, Neumann G, Tomasi N, Pinton R, Weisskopf L (2010) Release of plant-borne flavonoids into the rhizosphere and their role in plant nutrition. Plant Soil 329:1–25. doi:10.1007/s11104-009-0266-9
Cesco S, Mimmo T, Tonon G, Tomasi N, Pinton R, Terzano R, Neumann G, Weisskopf L, Renella G, Landi L, Nannipieri P (2012) Plant-borne flavonoids released into the rhizosphere: impact on soil bio-activities related to plant nutrition. A review. Biol Fertil Soils 48:123–149. doi:10.1007/s00374-011-0653-2
Colombo C, Palumbo G, Sellitto VM, Rizzardo C, Tomasi N, Pinton R, Cesco S (2012) Characteristics of insoluble, high molecular weight iron-humic substances used as plant iron sources. Soil Sci Soc Am J 76:1246–1256
Colombo C, Palumbo G, He J, Pinton R, Cesco S (2014) Review on Iron availability in soil: interaction of Fe minerals, plants and microbes. J Soils Sediments 14:538–548
Conyers MK, Uren NC, Helyar KR (1995) Causes of changes in pH in acid mineral soils. Soil Biol Biochem 27:1383–1392
Dakora FD, Phillips DA (2002) Root exudates as mediators on mineral acquisition in low-nutrient environments. Plant Soil 245:35–47
Dessureault-Rompré J, Nowack B, Schulin R, Luster J (2006) Modified micro suction cup/rhizobox approach for the insitu detection of organic acids in rhizosphere soil solution. Plant Soil 286:99–107
Dieffenbach A, Göttlein A, Matzner E (1997) In-situ soil solution chemistry in an acid forest soil as influenced by growing roots of Norway spruce (Picea abies [L.] Karst.). Plant Soil 192:57–61
Ding SM, Sun Q, Xu D, Jia F, He X, Zhang CS (2011) High-resolution simultaneous measurements of dissolved reactive phosphorus and dissolved sulfide: the first observation of their simultaneous release in sediments. Environ Sci Technol 46(15):8297–8304
FAO (2006) World Agriculture: towards 2030/2050, Interim Report. Prospects for Food, Nutrition, Agriculture and Major Commodity Groups. Global Perspective Studies Unit, Food and Agriculture Organization of the United Nations, Rome, Italy
Funayama-Noguchi S, Noguchi K, Terashima I (2014) Comparison of the response to phosphorus deficiency in two lupin species, Lupinus albus and L. angustifolius, with contrasting root morphology. Plant Cell Environ. doi:10.1111/pce.12390
Gruwel MLH (2014) In situ magnetic resonance imaging of plant roots. Vadose Zone J 13:3
Hinsinger P, Plassard C, Tang C, Jaillard B (2003) Origins of root mediated pH changes in the rhizosphere and their responses to environmental constraints: a review. Plant Soil 248:43–59
Hodge A, Grayston SJ, Ord BG (1996) A novel method for soil characterization and quantification of plant root exudates. Plant Soil 184:97–104
Jones DL, Darrah PR, Kochian LV (1996) Critical evaluation of organic acid mediated iron dissolution in the rhizosphere and its potential role in root iron uptake. Plant Soil 180:57–66
Kraemer SM, Crowley DE, Kretzschmar R (2006) Geochemical aspects of phytosiderophore-promoted iron acquisition by plants. Adv Agron 91:1–46
Kreuzeder A, Santner J, Prohaska T, Walter WW (2013) Gel for simultaneous chemical imaging of anionic and cationic solutes using diffusive gradients in thin films. Anal Chem 85:12028–12036
Lambers H, Clements JC, Nelson MN (2013) How a phosphorus-acquisition strategy based on carboxylate exudation powers the success and agronomic potential of lupines (Lupinus, Fabaceae). Am J Bot 100:263–288
Lemanceau P, Expert D, Gaymard F, Bakker PAHM, Briat JF (2009) Role of iron in plant–microbe interactions. Adv Bot Res 51:491–549
Luster J, Göttlein A, Nowack B, Sarret G (2009) Sampling, defining, characterising and modeling the rhizosphere—the soil science tool box. Plant Soil 321:457–482
Mimmo T, Sciortino M, Ghizzi M, Gianquinto G, Gessa CE (2009) The influence of aluminium availability on phosphate uptake in Phaseolus vulgaris L. and Phaseolus lunatus L. Plant Physiol Biochem 47:68–72
Mimmo T, Hann S, Jaitz L, Cesco S, Gessa CE, Puschenreiter M (2011) Time and substrate dependent exudation of carboxylates by Lupinus albus L. and Brassica napus L. Plant Physiol Biochem 49:1272–1278
Mimmo T, Ghizzi M, Cesco S, Tomasi N, Pinton R, Puschenreiter M (2013) Aluminium-phosphate interactions in the rhizosphere of two bean species: Phaseolus lunatus L. and Phaseolus vulgaris L. J Sci Food Agric 93(15):3891–3896
Mimmo T, Del Buono D, Terzano R, Tomasi N, Vigani G, Crecchio C, Pinton R, Zocchi G, Cesco S (2014) Rhizospheric organic compounds in the soil-microorganism-plant system: their role in iron availability. Eur J Soil Sci. doi:10.1111/ejss.12158
Neumann G, Römheld V (2007) The release of root exudates as affected by the plant’s physiological status. In: Pinton R, Varanini Z, Nannipieri P (eds) The rhizosphere: biochemistry and organic substances at the soil–plant interface. CRC, Boca Raton, pp 23–72
Neumann G, George TS, Plassard C (2009) Strategies and methods for studying the rhizosphere – the plant science toolbox. Plant Soil 321:431–456
Oburger E, Dell’mour M, Hann S, Wieshammer G, Puschenreiter M, Wenzel WW (2013) Evaluation of a novel tool for sampling root exudates from soil-grown plants compared to conventional techniques. Environ Exp Bot 87:235–247
Oburger E, Gruber B, Schindlegger Y, Schenkeveld WDC, Hann S, Kraemer SM, Wenzel W, Puschenreiter M (2014) Root exudation of phytosiderophores from soil grown wheat. New Phytol. doi:10.1111/nph.12868
PAR (2010) Biodiversity for Food and Agriculture: Contributing to food security and sustainability in a changing world. Outcomes of an expert Workshop held by FAO and the Platform on Agrobiodiversity Research (PAR) Rome, Italy, 2010. Available at: http://www.fao.org/fileadmin/templates/biodiversity_paia/PAR-FAO-book_lr.pdf
Reichard PU, Kraemer SM, Frazier SW, Kretzschmar R (2005) Goethite dissolution in the presence of phytosiderophores: rates, mechanisms, and the synergistic effect of oxalate. Plant Soil 276:115–132
Reichard PU, Kretzschmar R, Kraemer SM (2007) Dissolution mechanisms of goethite in the presence of siderophores and organic acids. Geochim Cosmochim Acta 71:5635–5650
Römheld V (1991) The role of phytosiderophores in acquisition of iron and other micronutrients in graminaceous species – an ecological approach. Plant Soil 130:127–134
Schenkeveld WDC and Kraemer SM (2014) Equilibrium and kinetic modelling of the dynamic rhizosphere. Plant Soil in press
Schenkeveld WDC, Oburger E, Gruber B, Schindlegger Y, Hann S, Puschenreiter M, Kraemer SM (2014) Metal mobilization from soils by phytosiderophores - experiment and equilibrium modeling. Plant Soil. doi:10.1007/s11104-014-2128-3
Schreiber CM, Zeng B, Blossfeld S, Rascher U, Kazda M, Schurr U, Höltkemeier A, Kuhn AJ (2012) Monitoring rhizospheric pH, oxygen, and organic acid dynamics in two short-time flooded plant species. J Plant Nutr Soil Sci 175:761–768
Shen J, Hoffland E (2007) In situ sampling of small volumes of soil solution using modified micro-cups. Plant Soil 292:161–169
Six L, Pypers P, Degryse F, Smolders E, Merckx R (2012) The performance of DGT versus conventional soil phosphorus tests in tropical soils—an isotope dilution study. Plant Soil 359:267–279
Stockdale A, Davison W, Zhang H (2008) High-resolution two-dimensional quantitative analysis of phosphorus, vanadium and arsenic, and qualitative analysis of sulfide, in a freshwater sediment. Environ Chem 5(2):143–149
Tomasi N, Kretzschmar T, Espen L, Weisskopf L, Fuglsang AT, Palmgren MG, Neumann G, Varanini Z, Pinton R, Martinoia E, Cesco S (2009) Plasma membrane H+-ATPase-dependent citrate exudation from cluster roots of phosphate-deficient white lupin. Plant Cell Environ 32:465–475
von Wirén N, Römheld V, Morel JL, Guckert A, Marschner H (1993) Influence of microorganisms on iron acquisition in maize. Soil Biol Biochem 25:371–376
Wang Z, Göttlein A, Bartonek G (2001) Effects of growing roots of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.) on rhizosphere soil solution chemistry. J Plant Nutr Soil Sci 164:35–41
Wang Z, Straub D, Yang H, Kania A, Shen J, Ludwig U, Neumann G (2014) The regulatory network of cluster-root function and development in phosphate-deficient white lupin (Lupinus albus) identified by transcriptome sequencing. Physiol Plant 151:323–338
White PJ (2012) Ion uptake mechanisms of individual cells and roots: short-distance transport. In: Marschner P (ed) Marschner’s mineral nutrition of higher plants. Academic, London, pp 7–47
Windt CW, Soltner H, van Dusschoten D, Blümler PJ (2011) A portable Halbach magnet that can be opened and closed without force: the NMR-CUFF. J Magn Reson 208:27–33
Zhang H, Zhao FJ, Sun B, Davison W, McGrath SP (2001) A new method to measure effective soil solution concentration predicts copper availability to plants. Environ Sci Technol 35:2602–2607
Zhang F, Shen J, Zhang J, Zuo Y, Li L, Chen X (2010) Rhizosphere processes and management for improving nutrient use efficiency and crop productivity: implications for China. Adv Agron 107:1–32. doi:10.1016/S0065-2113(10)07001-X, 1st ed
Research supported by grants from Italian MIUR (FIRB - Programma “Futuro in Ricerca”) and Free University of Bolzano (TN5056 - TN2023).
Responsible Editor: Michael A. Grusak.
About this article
Cite this article
Terzano, R., Cesco, S. & Mimmo, T. Dynamics, thermodynamics and kinetics of exudates: crucial issues in understanding rhizosphere processes. Plant Soil 386, 399–406 (2015). https://doi.org/10.1007/s11104-014-2308-1
- Root exudates
- Thermodynamics vs. kinetics