title: Turgor regulation in osmotically stressed Arabidopsis epidermal root cells. Direct support for the role of inorganic ion uptake as revealed by concurrent flux and cell turgor measurements.
abstract: Hyperosmotic stress is known to significantly enhance net uptake of inorganic ions into plant cells. Direct evidence for cell turgor recovery via such a mechanism, however, is still lacking. In the present study, we performed concurrent measurements of net ion fluxes (with the noninvasive microelectrode ion flux estimation technique) and cell turgor changes (with the pressure-probe technique) to provide direct evidence that inorganic ion uptake regulates turgor in osmotically stressed Arabidopsis epidermal root cells. Immediately after onset of hyperosmotic stress (100/100 mM mannitol/sorbitol treatment), the cell turgor dropped from 0.65 to about 0.25 MPa. Turgor recovery started within 2 to 10 min after the treatment and was accompanied by a significant (30-80 nmol m-2 s-1) increase in uptake of K+, Cl-, and Na+ by root cells. In most cells, almost complete (>90% of initial values) recovery of the cell turgor was observed within 40 to 50 min after stress onset. In another set of experiments, we combined the voltage-clamp and the microelectrode ion flux estimation techniques to show that this process is, in part, mediated by voltage-gated K+ transporters at the cell plasma membrane. The possible physiological significance of these findings is discussed.
authors: School of Agricultural Science, University of Tasmania, Hobart, Australia.
authors: Sergey N
authors: SN
authors: Shabala
authors: Roger R
authors: RR
authors: Lew
mesh_terms: D017360:Arabidopsis / Q000502:physiology*; D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D004867:Equipment Design; D007477:Ions / Q000378:metabolism; D008353:Mannitol / Q000494:pharmacology; D008564:Membrane Potentials / Q000502:physiology; D009997:Osmotic Pressure; D018408:Patch-Clamp Techniques; D019441:Plant Epidermis / Q000502:physiology*; D018517:Plant Roots / Q000502:physiology*; D011188:Potassium / Q000378:metabolism; D024642:Potassium Channels, Voltage-Gated / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D013012:Sorbitol / Q000494:pharmacology; D013314:Stress, Mechanical
chemical_list: D002712:Chlorides; D007477:Ions; D024642:Potassium Channels, Voltage-Gated; D008353:Mannitol; D013012:Sorbitol; D012964:Sodium; D011188:Potassium