Differential proton secretion in the apical elongation zone caused by gravistimulation is induced by a signal from the root cap

Plant Cell Environ. 1996 Dec;19(12):1408-14. doi: 10.1111/j.1365-3040.1996.tb00019.x.


The extracellular proton activity along primary roots of Phleum pratense L. was measured using proton-selective microelectrodes. Removal of the root cap caused a reduction of the proton influx in the transitional region between the meristem and the apical elongation zone of the vertical root and inhibited the development of pH differences between the physically upper and lower flanks of the gravistimulated root. Disruption of the actin filament system of the root with 5 mmol m-3 cytochalasin D did not result in an altered proton flux and pH pattern compared with untreated vertical control roots, but inhibited the gravity-induced development of pH differences between the physically upper and lower root flanks as well as gravitropic curvature. These results provide evidence that pH changes following gravistimulation are induced by a signal transmitted from the root cap and that the actin filament system is involved in the gravity perception/transduction mechanism.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cytochalasin D / pharmacology
  • Cytoskeleton / drug effects*
  • Cytoskeleton / physiology
  • Gravitation
  • Gravitropism / drug effects*
  • Gravitropism / physiology
  • Gravity Sensing / drug effects
  • Gravity Sensing / physiology*
  • Hydrogen-Ion Concentration / drug effects
  • Meristem / growth & development
  • Meristem / metabolism
  • Microelectrodes
  • Nucleic Acid Synthesis Inhibitors / pharmacology
  • Plant Root Cap / drug effects
  • Plant Root Cap / growth & development*
  • Plant Root Cap / metabolism
  • Plant Roots / drug effects
  • Plant Roots / growth & development*
  • Plant Roots / metabolism
  • Poaceae / drug effects
  • Poaceae / growth & development
  • Poaceae / metabolism
  • Protons*
  • Signal Transduction / drug effects
  • Signal Transduction / physiology


  • Nucleic Acid Synthesis Inhibitors
  • Protons
  • Cytochalasin D