Solute is imported to elongating root cells of barley as a pressure driven flow of solution

Jeremy Pritchard, N Gould, MR Thorpe, PEH Minchin, PJ White

Research output: Contribution to journalArticle

30 Citations (Scopus)


This work relates solute import to elongating root cells in barley to the water relations of the symplastic pathway under conditions of varied plant K+ status. K+ is a major constituent of phloem sieve element (SE) sap, and as an osmoticum, it is believed to have a role in maintaining SE hydrostatic pressure and thus sap flow from source to sink tissue. The hypothesis that the solute import to elongating root cells is linked to pressure driven flow from the sieve tube is examined. Plants were grown in solutions containing either 0.05 m M (low K) or 2.05 m M (high K) K+ concentration. Solute import to the root elongation zone was estimated from biomass accumulation over time accounting for respiration and root elongation rate. SE sap K+ concentration was measured using X-ray microanalyses and osmotic pressure by picolitre osmometry. SE hydrostatic pressure was measured directly with a pressure probe glued onto an excised aphid stylet. Elongating root cell hydrostatic pressure was measured using a cell pressure probe. The low-K plants had lower SE K+ concentration and SE hydrostatic pressure compared to the high-K plants, but the elongating root cell hydrostatic pressure was similar in both treatments, thus the pressure difference between the SE and elongating root cells was less in the low-K plants compared to the high-K plants. The solute import rate to elongating root cells was lower in the low K plants and the reduction could be accounted for as a pressure driven solute flux, with a reduction both in the pressure difference between root sieve elements and elongating cells, and in the sap concentration.
Original languageEnglish
Pages (from-to)391-397
Number of pages7
JournalFunctional Plant Biology
Publication statusPublished - 1 Jan 2004


  • solute transport
  • Hordeum vulgare
  • symplastic pathway
  • aphid stylectomy
  • C-11
  • phloem
  • hydrostatic pressure


Dive into the research topics of 'Solute is imported to elongating root cells of barley as a pressure driven flow of solution'. Together they form a unique fingerprint.

Cite this