Advertisement

Plant and Soil

, Volume 153, Issue 1, pp 47–59 | Cite as

Re-sorption of organic compounds by roots of Zea mays L. and its consequences in the rhizosphere

II. Experimental and model evidence for simultaneous exudation and re-sorption of soluble C compounds
  • D. L. Jones
  • P. R. Darrah
Research Article

Abstract

The exudation of soluble carbon compounds from Zea mays roots was investigated over a 10 day growth period under sterile and non-sterile solution culture conditions. The results showed that plants grown in sterile static solution culture, where C was allowed to accumulate, released 8 times less C than plants grown under culture conditions in which the solutions were replaced daily.

The increased C loss from plant cultures in which exudates were removed daily was attributable to, (a) the reduced potential for root re-sorption of previously lost C, and (b), increasing diffusion gradients between the root and the surrounding bathing solution increasing passive leakage of exudates from the roots. In treatments where C was removed daily from the root-bathing solution, 86% of the total C lost was of a soluble low molecular weight nature, whereas, in sterile and non-sterile static cultures, allowing the accumulation of C over 10 days, this was reduced to 67.5 and 48% respectively.

The main C fluxes operating in a solution culture system (efflux and influx of C by both roots and microorganisms) were examined using a computer simulation model to describe movement of soluble sugar-C in both sterile and non-sterile conditions. In sterile static cultures where C was allowed to accumulate in solution over a 10 day growth period, 98% of the C exuded was re-absorbed by the plant. Where C was removed daily from the root-bathing solution this was reduced to 86%. The predicted patterns of C accumulation were similar to those found in the experiments. Simulations showed that the pattern of accumulation and final equilibrium concentrations were dependent on the rate of exudation, the spatial characteristics of exudation, solution volume, root growth rate and the presence of a microbial population. Simulations under non-sterile conditions showed that roots can compete with microorganisms for exudates in solution indicating the possible importance of re-sorption in a soil environment.

The results clearly indicate that roots are capable of regulating the net amount of C released into a solution culture with the amount of C collected being highly dependent on the experimental conditions employed. The possible implications of soluble C influx on processes operating within the rhizosphere and in experimental systems is discussed.

Key words

maize mathematical model re-sorption rhizosphere root exudates 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Barber D A and Gunn K B 1974 The effect of mechanical forces on the exudation of organic substances by the roots of cereal plants grown under sterile conditions. New Phytol. 73, 39–45.Google Scholar
  2. Biondini M, Klein D A and Redente E F 1988 Carbon and nitrogen losses through root exudation by Agropyron cristatum, A. smithii and Bouteloua gracilis. Soil Biol. Biochem. 20, 477–482.CrossRefGoogle Scholar
  3. Bowen G D and Rovira A D 1973 Are models useful in rhizosphere biology? Bull. Ecol. Res. Comm. 17 443–450.Google Scholar
  4. Bradford M M 1976 A rapid and sensitive method of μg quantification of protein using the principle of protein-dye binding. Anal. Biochem. 72, 248–254.PubMedCrossRefGoogle Scholar
  5. Briskin D P and Hanson J B 1992 How does the plant plasma membrane H+-ATPase pump protons? J. Exp. Bot. 43, 269–289.Google Scholar
  6. Cakmak I and Marschner H 1988 Increase in membrane permeability and exudation in roots of zinc deficient plants. J. Plant Physiol. 132, 356–361.Google Scholar
  7. Chaboud A 1983 Isolation, purification and chemical composition of maize root cap slime. Plant and Soil 73, 395–402.CrossRefGoogle Scholar
  8. Chaboud A and Rougier M 1984 Identification and localization of sugar components of rice (Oryza sativa L.) root cap mucilage. J. Plant Physiol. 116, 323–330.Google Scholar
  9. Chen T H, Chen T L, Hung L M and Huang T C 1991 Circadian rhythm in amino acid uptake by Synechococcus RF-1. Plant Physiol. 97, 55–59.Google Scholar
  10. Coody P N, Sommers L E and Nelson D W 1986 Kinetics of glucose uptake by soil microorganisms. Soil Biol. Biochem. 18, 283–289.CrossRefGoogle Scholar
  11. Curl E A and Truelove B 1986 The Rhizosphere. Springer-Verlag, Berlin.Google Scholar
  12. Darrah P R 1991a Models of the rhizosphere. I. Microbial population dynamics around a root releasing soluble and insoluble carbon. Plant and Soil 133, 187–199.CrossRefGoogle Scholar
  13. Easton G D and Nagle M E 1985 Timing and root absorption affecting efficiency of metalaxyl in controlling Phytophthora infestans on potato in northest Washington state. Plant Disease 69, 499–500.Google Scholar
  14. Ebell L F 1969 Variation in total soluble sugars of conifer tissues with method of analysis. Phytochemistry 8, 277–233.Google Scholar
  15. Griffin G J, Hale M G and Shay F J 1976 Nature and quantity of sloughed organic matter produced by roots of axenic plants. Soil Biol. Biochem. 8, 29–32.CrossRefGoogle Scholar
  16. Haller T and Stolp H 1985 Quantitative estimation of root exudation in maize plants. Plant and Soil 86, 207–216.CrossRefGoogle Scholar
  17. Hoffland E 1992 Quantitative evaluation of the role of organic acid exudation in the mobilization of rock phosphate by rape. Plant and Soil 140, 279–289.Google Scholar
  18. Holden J 1975 Use of nuclear staining to assess the rates of cortical cell death in cortices of cereal roots, Soil Biol. Biochem. 7, 333–334.CrossRefGoogle Scholar
  19. Horst W J, Wagner A Marschner H 1982 Mucilage protects roots meristems from aluminium injury. Z. Pflanzenphysiol. 105, 435–444.Google Scholar
  20. Jones D L and Darrah P R 1992a Re-sorption of organic compounds by roots of Zea mays L. and its consequences in the rhizosphere I. Re-sorption of glucose, mannose and citric acid. Plant and Soil 143, 259–266.CrossRefGoogle Scholar
  21. Jones D L and Darrah P R 1993 Re-sorption of organic compounds by roots of Zea mays L. and its consequences in the rhizosphere. III. Spatial and selectivity characteristics of influx and the factors controlling efflux. Plant Physiol. submitted.Google Scholar
  22. Kraffczyk I, Trolldeiner G and Beringer H 1984 Soluble root exudates of maize: Influence of potassium supply and rhizosphere microorganisms. Soil Biol. Biochem. 16, 315–322.CrossRefGoogle Scholar
  23. Liljeroth E, Baath E, Mathiasson I and Lundborg T 1990 Root exudation and rhizoplane bacterial abundance of barley (Hordeum vulgare L.) in relation to nitrogen fertilization and root growth. Plant and Soil 127, 81–89.Google Scholar
  24. Matsumoto H, Okada K and Takahashi E 1979. Excreting products of maize roots from seedling to seed development stage. Plant and Soil 53, 17–26.CrossRefGoogle Scholar
  25. Meiners S, Gharyal P K and Schindler M 1991 Permeabilization of the plasmalemma and wall of soyabean root cells to macromolecules. Planta 184, 443–447.CrossRefGoogle Scholar
  26. Mench M, Morel J L, Guckert A and Guillert B 1988 Metal binding with root exudates of low molecular weight. J. Soil Sci. 39, 521–527.Google Scholar
  27. Mench M and Martin E 1991 Mobilization of cadmium and other metals from two soils by root exudates of Zea mays L., Nicotiana tabacum L. and Nicotiana rustica L., Plant and Soil 132, 187–196.Google Scholar
  28. Merckx R, Ginkel G H, Sinnaeve J and Cremers A 1986 Plant induced changes in the rhizosphere of maize and wheat. I. Production and turnover of root-derived material in the rhizosphere of maize and wheat. Plant and Soil 96, 85–93.Google Scholar
  29. Moore S and Stein W H 1948 Photometric ninhydrin method for use in the chromatography of amino acids. J. Biol. Chem. 176, 367–388.Google Scholar
  30. Mozafar A and Oertli J J 1992 Uptake of microbially-produced vitamin (B12) by soyabean roots. Plant and Soil 139, 23–30.Google Scholar
  31. Reinhold L and Kaplan A 1984 Membrane transport of sugars and amino acids. Annu. Rev. Plant Physiol. 35, 45–83.CrossRefGoogle Scholar
  32. Romheld V 1991 The role of phytosiderophores in acquisition of iron and other micronutrients in graminaceous species: An ecological approach. Plant and Soil 130, 127–134.Google Scholar
  33. Shay F J and Hale M G 1973 Effect of low levels of calcium on exudation of sugars and sugar derivatives from intact peanut roots under axenic conditions. Plant Physiol. 51, 1061–1063.Google Scholar
  34. Swain T and Hillis W E 1959 The phenolic content of Prunus domestica. I. The quantitative analysis of phenolic constituents. J Sci. Food Ag. 10, 63–68.Google Scholar
  35. Tagaki S, Nomoto K and Takemoto T 1984 Physiological aspect of muginieic acid, a possible phytosiderophore of Graminaceous plants. J. Plant Nutr. 7, 469–477.Google Scholar
  36. Trofymow J A, Coleman D C and Cambardella C 1987 Rates of rhizodeposition and ammonium depletion in the rhizosphere of axenic oat roots. Plant and Soil 97, 333–344.Google Scholar
  37. Uren N C and Reisenauer H M 1988 The role of root exudates in nutrient acquisition. Adv. Plant Nutr. 3, 79–114.Google Scholar
  38. Vancura V and Hanzlikova A 1972 Root exudates in plants. IV. Differences in chemical composition of seed and seedlings exudates. Plant and Soil 36, 271–282.Google Scholar
  39. Whipps J M 1985 Effect of CO2 concentration on growth, carbon distribution and loss of carbon from the roots of maize. J. Exp. Bot. 36, 644–651.Google Scholar
  40. Xia J and Saglio H 1988 Characterization of the hexose transport in maize root tips. Plant Physiol. 88, 1015–1020.Google Scholar

Copyright information

© Kluwer Academic Publishers 1993

Authors and Affiliations

  • D. L. Jones
    • 1
  • P. R. Darrah
    • 1
  1. 1.Department of Plant SciencesUniversity of OxfordOxfordUK

Personalised recommendations