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Journal of Plant Research

, Volume 110, Issue 4, pp 435–442 | Cite as

Mercurial-sensitive water transport in barley roots

  • Masashi Tazawa
  • Eiji Ohkuma
  • Mineo Shibasaka
  • Susumu Nakashima
Original Articles

Abstract

An isolated barley root was partitioned into the apical and basal part across the partition wall of the double-chamber osmometer. Transroot water movement was induced by subjecting the apical part to a sorbitol solution, while the basal part with the cut end was in artificial pond water. The rate of transroot osmosis was first low but enhanced by two means, infilitration of roots by pressurization and repetition of osmosis. Both effects acted additively. The radial hydraulic conductivity (Lpr) was calculated by dividing the initial flow rate with the surface area of the apical part of the root, to which sorbitol was applied, and the osmotic gradient between the apical and basal part of the root. Lpr which was first 0.02–0.04 pm s−1 Pa−1 increased up to 0.25–0.4 pm s−1 Pa−1 after enhancement. Enhancement is assumed to be caused by an increase of the area of the plasma membrane which is avallable to osmotic water movement. The increased Lpr is in the same order of magnitude as the hydraulic conductivity (Lp) of epidermal and cortical cells of barley roots obtained by Steudie and Jeschke (1983). HgCl2, a potent inhibitor of water channels, suppressed Lpr of non-infiltrated and infiltrated roots down to 17% and 8% of control values, respectively. A high sensitivity of Lpr to HgCl2 suggests that water channels constitute the most conductive pathway for osmotic radial water movement in barley roots.

Key words

Barley root HgCl2 Hydraulic conductivity Infiltration Transroot osmosis Water channels 

Abbreviations

APW

artificial pond water

Jv

rate of transroot osmosis

Lp

hydraulic conductivity of plasma membrane

Lpr

radial hydraulic conductivity of root

ME

2-mercaptoethanol

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References

  1. Henzier, T. andSteudle, E. 1995. Reversible closing of water channels inChara internodes provides evidence for a composite transport model of the plasma membrane. J. Exp. Bot.46: 199–209.Google Scholar
  2. Heydt, H. andSteudle, E. 1991. Measurement of negative pressure in the xylem of excised roots. Planta184: 389–396.CrossRefGoogle Scholar
  3. Kaldenhoff, R., Kölling, A., Meyers, J., Karmann, U., Ruppel, G. andRichter, G. 1995. The blue light-responsive AthH2 gene ofArabidopsis thaliana is primarily expressed in expanding as well as in differentiating cells and encodes a putative channel protein of the plasma membrane. Plant J.7: 87–95.PubMedCrossRefGoogle Scholar
  4. Kamiya, N. andTazawa, M. 1956. Studies on water permeability of a single plant cell by means of transcellular osmosis. Protoplasma46: 394–422.CrossRefGoogle Scholar
  5. Kammerloher, W., Fischer, U., Plechottka, G.P. andSchäffner, A.R. 1994. Water channels in plant plasma membrane cloned by immunoselection from a mammalian expression system. Plant J.6: 187–199PubMedCrossRefGoogle Scholar
  6. Kramer, P.J. 1983. Water Relations of Plants. Academic Press, New York.Google Scholar
  7. Maeshima, M. 1992. Characterization of the major integral protein of vacuolar membrane. Plant Physiol.98: 1248–1254.PubMedCrossRefGoogle Scholar
  8. Maeshima, M., Nakanishi, Y., Matsuura-Endo, C., andTanaka, Y.J. 1996. Proton pumps of the vacuolar membrane in growing plant cells. J. Plant Res.109: 119–125.CrossRefGoogle Scholar
  9. Maggio, A. andJoly, R.J. 1995. Effects of mercuric chloride on the hydraulic conductivity of tomato root systems. Plant Physiol.109: 331–335.PubMedGoogle Scholar
  10. Maurel, C., Reizer, J., Schroeder, J.I. andChrispeels, M.J. 1993. The vacuolar membrane protein—TIP creates water channels inXenopus oocytes. EMBO J.12: 2241–2247.PubMedGoogle Scholar
  11. Ohya, M. 1996. Changes of uptake and translocation of K+ during root development. Master Thesis, Graduate School of Agricul ture, Okayama University (in Japanese)Google Scholar
  12. Passioura, J.B. 1988. Water transport in and to roots. Annu. Rev. Plant Physiol. Plant Mol. Biol.39: 245–265.CrossRefGoogle Scholar
  13. Peterson, C.A., Murrmann, M. andSteudle, E. 1983. Location of the major barriers to water and ion movement in young roots ofZea mays L. Planta190: 127–136.Google Scholar
  14. Preston, G.M., Carroll, T.P., Guggino, W.P. andAgre, P. 1992. Appearance of water channels inXenopus oocytes expressing red cell CHIP28 protein. Science256: 385–387.PubMedCrossRefGoogle Scholar
  15. Steudle, E. andJeschke, W.D. 1983. Water transport in barley roots. Planta158: 237–248.CrossRefGoogle Scholar
  16. Steudle, E., Murrmann, M. andPeterson, C.A. 1993. Transport of water and solutes across maize roots modified by puncturing the endodermis. Plant Physiol.103: 335–349.PubMedGoogle Scholar
  17. Steudle, E., Oren, R. andSchulze, E. -D. 1987. Water transport in maize roots. Plant Physiol.84: 1220–1232.PubMedGoogle Scholar
  18. Tazawa, M., Asai, K. andIwasaki, N. 1996. Characteristics of Hg- and Zn-sensitive water channels in the plasma membrane ofChara cells. Bot. Acta109: 388–396.Google Scholar
  19. Wayne, R. andTazawa M. 1990. Nature of the water channels in the internodal cells ofNitellopsis. J. Membr. Biol.116: 31–39.PubMedCrossRefGoogle Scholar
  20. Yamada, S., Katsuhara, M., Kelly, W.B., Michalowski, V.B. andBohnert, H.J. 1995. A family of transcripts encoding water channel proteins: tissue specific expression in the common ice plant. Plant Cell7: 1129–1142.PubMedCrossRefGoogle Scholar

Copyright information

© The Botanical Society of Japan 1997

Authors and Affiliations

  • Masashi Tazawa
    • 1
  • Eiji Ohkuma
    • 2
  • Mineo Shibasaka
    • 2
  • Susumu Nakashima
    • 2
  1. 1.Department of Applied Physics and ChemistryFukui University of TechnologyFukuiJapan
  2. 2.Research Institute for BioresourcesOkayama UniversityKurashikiJapan

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