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


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 



artificial pond water


rate of transroot osmosis


hydraulic conductivity of plasma membrane


radial hydraulic conductivity of root




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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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