The role of Ca2+, H+, and Cl− ions in generation of variation potential in pumpkin plants

The role of Ca2+, H+, and Cl− ions in generation of variation potential in pumpkin plants The contributions of Ca2+, H+, and Cl− in generation of variation potentials (VP) in 3- to 4-week-old pumpkin (Cucurbita pepo L., cv. Mozoleevskaya) plants were assessed. During VP generation, transient alkalinization of the medium around the stem was recorded with a potentiometric method. The pH changes were kinetically similar to the electric potential changes and were apparently due to temporal suppression of the plasma-membrane electrogenic H+ pump. These data and the observed inhibition of VP in the stem zone treated locally with a metabolic inhibitor (NaN3) indicate that the VP generation is related to the reversible suppression of the H+-pump. The anion channel blocker (ethacrynic acid) decelerated significantly the front slope of VP and reduced the VP amplitude. A short-term increase in external Cl− concentration around the stem was observed during potential transients representing the VP front slope and the pulses integrated into VP. The removal of Ca2+ from extracellular medium inhibited the VP generation. It is proposed that Ca2+ plays a role in activation of anion channels and in the H+-pump inactivation. The VP generation is probably determined by a complex mechanism, with contributions from passive ion fluxes (Ca2+, Cl−) moving along the electrochemical gradients and from changes in the electrogenic pump activity. Russian Journal of Plant Physiology Springer Journals

The role of Ca2+, H+, and Cl− ions in generation of variation potential in pumpkin plants

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SP MAIK Nauka/Interperiodica
Copyright © 2011 by Pleiades Publishing, Ltd.
Life Sciences; Plant Physiology; Plant Sciences
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