Summary
A model based on the canal theory (Katou andFurumoto 1986 a, b) is proposed for the absorption of solute and water at the root periphery. The present canal model in the periphery and the model which was previously proposed for the exudation in the stele (Katou et al. 1987), are organized into a model for radial transport across excised plant roots, in the light of anatomical and physiological knowledge of maize roots. The canal equations for both canals are numerically solved to give quite a good explanation for the observed exudation of maize roots. It is found that the regulation of solute transport has a primary importance in the regulation of water transport across excised roots. The internal cell pressure of the symplast adjusts the water absorption at the root periphery to the water secretion into the vessels. There seems no need for this explanation of the radial water transport across roots to assume cell membranes with low reflection coefficient or variable water permeability. It would seem that the apoplast wall layers play a crucial role in metabolic control of water transport in roots as well as in hypocotyls.
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Abbreviations
- J ex*s :
-
the theoretically estimated rate of solute exudation per unit surface area of model maize roots
- J:
-
that of volume exudation per unit surface area of model maize roots
- σ:
-
the reflection coefficient of the cell membrane against solutes
References
Anderson WP (1975) Long distance transport in roots. In:Baker DA,Hall JL (eds) Ion transport in plant cells and tissues. North-Holland, pp 231–266
—,House CR (1967) A correlation between structure and function in the root ofZea mays. J Exp Bot 18: 544–555
—,Reilly EJ (1968) The effect of temperature on the exudation process of excised primary roots ofZea mays. J Exp Bot 19: 648–657
—,Aikman DP, Meiri A (1970) Excised root exudation. Proc Roy Soc London B 174: 445–458
Arisz WH, Helder RJ, van Nie R (1951) Analysis of the exudation process in tomato plants. J Exp Bot 2: 257–297
Bange GGJ (1973) Diffusion and absorption of ions in plant tissue. III. The role of the root cortex cells in ion absorption. Acta Bot Neerl 22: 529–542
Burley JWA, Nwoke FIO, Leister GL, Popham RA (1970) The relationship of xylem maturation to the absorption and translocation of P32. Am J Bot 57: 504–511
Clarkson DT, Robards AW, Stephens JE, Stark M (1987) Suberin lamellae in the hypodermis of maize (Zea mays) roots; Development and factors affecting the permeability of hypodermal layers. Plant Cell Environ 10: 83–93
Cosgrove DJ, Cleland RE (1987) Osmotic properties of pea internodes in relation to growth and auxin action. Plant Physiol 72: 332–338
Curran PF, MacIntosh JR (1962) A model system for biological water transport. Nature 193: 347–348
Dainty J, Kleinová M, Janáček K (1981) The movement of water across the plant root. In:Brouwer R, Gašparíková O, Kolek J, Loughman BC (eds) Structure and function of plant roots. Martinus Nijhoff/Dr W Junk, The Hague Boston London, pp 149–152
Drew MC (1987) Function of root tissues in nutrient and water transport. In:Gregory PJ, Lake JV, Rose DA (eds) Root development and function. Cambridge University Press, Cambridge, pp 72–101
—,Chamel A, Garrec J-P, Fourcy A (1980) Cortical air spaces (Aerenchyma) in roots of corn subjected to oxygen stress. Structure and influence on uptake and translocation of86Rubidium ions. Plant Physiol 65: 506–511
—,Saker LR (1986) Ion transport to the xylem in aerenchymatous roots ofZea mays L. J Exp Bot 37: 22–33
Dunlop J, Bowling DJF (1971) The movement of ions to xylem exudate of maize roots. I. Profiles of membrane potential and vacuolar potassium activity across the root. J Exp Bot 22: 434–444
Finkelstein A (1984) Water movement through membrane channels. Curr Topics Membr Transport 21: 295–308
Ginsburg H (1971) Model for iso-osmotic water flow in plant roots. J Theoret Biol 32: 147–158
—,Ginzburg BZ (1971) Evidence for active water transport in a corn root preparation. J Membr Biol 4: 29–41
Greaves MP, Darbyshire JF (1972) The ultrastructure of the mucilaginous layer on plant roots. Soil Biol Biochem 4: 443–449
Grunwaldt G, Ehwald R, Pietzsch W, Göring H (1979) A special role of the rhizodermis in nutrient uptake by plant roots. Biochem Physiol Pflanzen 174: 831–837
Guinel FC, McCully ME (1986) Some water-related physical properties of maize root-cap mucilage. Plant Cell Environ 9: 657–666
Higinbotham N, Davis RF, Mertz SM, Shumway LK (1973) Some evidence that radial transport in maize roots is into living vessels. In:Anderson WP (ed) Ion transport in plants. Academic Press, London New York, pp 493–506
Hymlö B (1953) Transpiration and ion absorption. Physiol Plant 6: 333–405
Katou K, Furumoto M (1986 a) A mechanism of respiration-dependent water uptake in higher plants. Protoplasma 130: 80–82
— — (1986 b) A mechanism of respiration-dependent water uptake enhanced by auxin. Protoplasma 133: 174–185
—,Taura T, Furumoto M (1987) A model for water transport in the stele of plant roots. Protoplasma 140: 123–132
Kochian LV, Lucas WJ (1983) Potassium transport in corn roots: The significance of the root periphery. Plant Physiol 73: 208–215
Kramer PJ (1983) Water relations of plants. Academic Press, Orlando
Läuchli A, Epstein E (1971) Lateral transport of ions into the xylem of corn roots. I. Kinetics and energetics. Plant Physiol 48: 111–117
—,Pitman MG, Kramer D, Ball E (1978) Are developing xylem vessels the site of ion exudation from root to shoot? Plant Cell Environ 1: 217–223
Malone CP, Burke JJ, Hanson JB (1977) Histochemical evidence for the occurrence of oligomycin-sensitive plasmalemma ATPase in corn roots. Plant Physiol 60: 916–922
Miller DM (1981) Pressure-flow characteristics of the roots ofZea mays In:Brouwer R, Gašpariková O, Kolek J, Loughman BC (eds) Structure and function of plant roots. Martinus Nijhoff/Dr W Junk, The Hague Boston London, pp 153–156
Nakahori K, Katou K, Okamoto H (1987) The role of membrane potential for the control of elongation growth ofVigna hypocoyl: Response of a hollow cylinder to osmotic stress and ionic stress. Plant Cell Physiol 28: 901–910
Oschman JL, Wall BJ, Gupta BL (1974) Cellular basis of water transport. Symp Soc Exp Biol 28: 305–350
Perumalla CJ, Peterson CA (1986) Deposition of Casparian bands and suberin lamellae in the exodermis and endodermis of young corn and onion roots. Can J Bot 64: 1873–1878
Peterson CA (1987) The exodermal Casparian band of onion roots blocks the apoplastic movement of sulphate ions. J Exp Bot 38: 2068–2081
—,Emanuel ME, Wilson C (1982) Identification of a Casparian band in the hypodermis of onion and corn roots. Can J Bot 60: 1529–1535
—,Perumalla CJ (1984) Development of the hypodermal Casparian band in corn and onion roots. J Exp Bot 35: 51–57
Pitman MG (1972) Uptake and transport of ions in barley seedlings. II. Evidence for two active stages in transport to the shoot. Aust J Biol Sci 25: 243–257
— (1982) Transport across plant roots. Quat Rev Biophys 15: 481–554
—,Wellfare D (1978) Inhibition of ion transport in excised barely roots by abscisic acid: relation to water permeability of the roots. J Exp Bot 29: 1125–1138
—,Wellfare D, Carter C (1981) Reduction of hydraulic conductivity during inhibition of exudation from excised maize and barley roots. Plant Physiol 67: 802–808
Robards AW, Clarkson DT, Sanderson J (1979) Structure and permeability of the epidermal/hypodermal layers of sand sedge (Carex arenaria, L.). Protoplasma 101: 331–347
St Aubin G, Canny MJ, McCully ME (1986) Living vessel elements in the late metaxylem of sheathed maize roots. Ann Bot 58: 577–588
Steudle E, Jeschke WD (1983) Water transport in barley roots. Planta 158: 237–248
Vakhmistrov DB (1967) On the function of the apparent free space in plant roots. A study of the absorbing power of epidermal and cortical cells in barley roots. Fiziol Rastenii 14: 123–129
Van Iren F, Boer-Van der Sluijs P (1980) Symplasmic and apoplasmic radial ion transport in plant roots: Cortical plasmalemmas lose absorption capacity during differentiation. Planta 148: 130–137
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Taura, T., Iwaikawa, Y., Furumoto, M. et al. A model for radial water transport across plant roots. Protoplasma 144, 170–179 (1988). https://doi.org/10.1007/BF01637250
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DOI: https://doi.org/10.1007/BF01637250