The effects of freezing on membrane electric potential in winter oilseed rape leaves |
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Authors: | Grażyna Piotrowska Maria Filek Alina Kacperska |
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Institution: | (1) Institute of Experimental Plant Biology, Warsaw University, Pawińskiego 5A, PL-02-106 Warszawa;(2) F. Górski Department of Plant Physiology, Polish Academy of Sciences, Podłużna 3, 30-239 Kraków |
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Abstract: | Extracellular ice formation in winter oilseed rape leaf discs (Brassica napus L. var. oleifera L. cv. Jantar) at different temperatures resulted in a transient membrane depolarization, which was followed by a decrease
in membrane electric potential. In discs which underwent supercooling (no extracellular ice was formed), no membrane depolarization
was observed. The inhibitors of calcium ion channels, gadolinium and lanthanum, decreased to some extend the amplitude of
the frost-induced (−6 °C) depolarization and completely eliminated the decrease in membrane potential. Changes in membrane
potential were associated with the increased electrolyte efflux, measured after thawing of the discs. No efflux from supercooled
discs was observed. Application of calcium channel blockers decreased the level of the efflux induced by freezing at −6°C.
It is suggested that membrane depolarization is one of the primary events induced by ice formation at a leaf surface. The
possible reasons for changes in the membrane electric potential and their physiological consequences are discussed. |
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Keywords: | Brassica napus electrolyte efflux calcium channel inhibitors freezing gadolinium lanthanum leaves membrane potential winter oilseed rape |
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