
TY  - JOUR
A1  - Babourina, Olga 
A1  - Hawkins, Barbara 
A1  - Lew, Roger R. 
A1  - Newman, Ian 
A1  - Shabala, Sergey 
T1  - K<emph type="7">+</emph> transport by <emph type="2">Arabidopsis</emph> root hairs at low pH
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 2001
VL  - 28
IS  - 7
SP  - 637
EP  - 643
KW  - Arabidopsis, K+transport, low pH, membrane potential, root hair, voltage clamp.
UR  - https://doi.org/10.1071/PP01018 
N2  - Mechanisms underlying changed K + uptake by plantsat low pH need to be deciphered. One possibility is that K+ acquisition is under the strict control of plasmamembrane potential (E m ), which,in turn, is affected by external pH. To test this hypothesis, we used themicroelectrode ion flux measurement (MIFE ) technique tostudy net K + and H +fluxes near Arabidopsis root hairs at different externalpH, KCl concentrations and clamped Em . Lowering the solution pH led to strong H+ influx, K + efflux andsignificant E m depolarisation.Addition of K + to the bathing media causedsignificant net K + uptake when external pH wasover the range 5.5&#8211;6.0. At external pH below 5.0, however, correlationbetween K + availability and net K+ uptake was negative. To explain this apparentparadox, measurements of net K + and H+ fluxes from the root hair surface were performedconcurrently with E m clamped at different values above and below the restingpotential (approx. &#8211;180 mV). Our data revealed a strong dependence ofnet K + flux on the clamping voltage. Clamping atvalues more negative than the resting potential caused a significant increasein K + uptake into the root hair; clamping at lessnegative values (&#8211;20 and 0 mV) caused significant net K+ efflux from the cell. Qualitatively similarresults were observed for net H + flux. Ourobservations indicate direct control of K + flux bychanging E m , and suggest thatE m depolarisation could be themain reason for the observed K + efflux at low pH. 
ER  -

