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Oscillations in H+ and Ca2+ Ion Fluxes around the Elongation Region of Corn Roots and Effects of External pH

journal contribution
posted on 2023-05-16, 10:26 authored by Sergey ShabalaSergey Shabala, Ian NewmanIan Newman, Morris, J
Net fluxes of H + and Ca 2+ around the elongation region of low-salt corn (Zea mays L.) roots were measured using the microelectrode ion flux estimation (MIFE) technique. At pH 5.2 two oscillatory components were found. Fast, 7-min oscillations in H + flux were superimposed on slow oscillations of about 1.5 h. Fast oscillations in Ca 2+ flux showed a strong dependence on the H + oscillations and were normally leading in phase by about 1 to 1.5 min. Both oscillatory components were strongly affected by external pH values. Preincubation for 20 h in buffered pH 4.0 solution suppressed the slow oscillatory component and caused huge H + influxes in the elongation region. The fast oscillations were 8 times larger in amplitude and were slightly lengthened. Preincubation at pH 6.0 did not suppress the rhythmic character of the ion fluxes but it shifted the average H + flux to greater efflux. The fast and slow oscillatory components of H + flux seem to relate to biophysical and biochemical mechanisms of intracellular pH homeostasis, respectively. The origin of the Ca 2+ flux oscillations is discussed in terms of the 'weak acid Donnan Manning' model of cell wall ion exchanges.

History

Publication title

Plant Physiology

Volume

113

Pagination

111-118

ISSN

0032-0889

Department/School

School of Natural Sciences

Publisher

American Society of Plant Physiologists

Place of publication

Rockville, USA

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the physical sciences

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