Journal Article

Action Potentials Evoked by Light in Traps of <i>Dionaea muscipula</i> Ellis

Kazimierz Trebacz and Andreas Sievers

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 39, issue 4, pages 369-372
Published in print April 1998 | ISSN: 0032-0781
Published online April 1998 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/oxfordjournals.pcp.a029379
Action Potentials Evoked by Light in Traps of Dionaea muscipula Ellis

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At low light intensities (less than 50 μmol m−2 s−1) illumination evokes transient depolarization of membrane potential in mesophyll cells of the leaf-trap of Dionaea muscipula Ellis. Darkening causes hyperpolarization approximately symmetric to the response to illumination. The amplitude as well as the rate of potential changes depend on light intensity. After exceeding a definite threshold (usually between 50 and 80 μmol m−2s−1) the depolarization plays the role of a generator potential and an all-or-none action potential (AP) is released. Switching light off in a depolarization phase of an AP does not change its shape and the amplitude. When the light intensity is increased to 80–150 μmol m−2 s−1 a single light stimulus triggers two successive APs. The time interval between the two APs decreases with increasing stimulus strength and reaches the minimum between 300 and 400 μmol m−2 s−1. At higher light intensities the interval increases again, and finally only a single AP is triggered. It was shown that the effect was evoked by light but not by temperature change accompanying illumination. An inhibitor of the photosyn-thetic electron transport chain, DCMU, blocked the generator potentials mediating between light absorption and APs. Residual responses to light stimuli in plants treated with DCMU had reverse polarity and strongly reduced the amplitudes.

Keywords: Action potential; Dionaea muscipula; Droseraceae; Venus flytrap

Journal Article.  0 words. 

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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