Light‐triggered action potentials in the liverwort Conocephalum conicum

Abstract

T. 1985. Light-triggered action potentials in the liverwort Conocephalum conicum. -Physiol. Plant. 64: 482-486.The response to light of a liverwort, Conocephalum conicum L., measured as a change in the resting potential, consists of two stages. The first stage is a slight depolarization dependent on light intensity. This plays the role of a generator potential (GP) which induces the second stage -an action potential of the all-or-none character. Action potentials induced by light and by electrical stimuli have the same properties, i.e. identical time course, propagation velocity, and refractory periods. A summation occurs of subthreshold light stimuli and of light and electrical stimuli. The presence of 5-10^ M DCMU cancelled the light response and blocked -by inhibition of the electron transport chain -the mechanism leading to GP generation. However, this effect did not produce any change in the response to electrical stimuli.Additional key words -Action potential, generator potential, stimulus. K. Tr(bacz (reprint requests) and T. Zawadzki,

Shade-Induced Action Potentials inHelianthus annuusL. Originate Primarily from the Epicotyl

“…The latter possibility is subject to direct experimental verification and may relate to the known facts (1) that propagation rates and decrement vary considerabley among sunflower plants (2) that altered xylem pressure and other internal factors amplify or reduce the electrical responses of plant cells 48 and (3) that different factors are known to undergo summation in the lowering of the spike-triggering depolarization level. 34,36 …”

“…1-3). Assuming that these APs require some generator potential for their triggering as well, [33][34][35][36] this difference could suggest that leaf-generated APs originate in the leaf epidermis while stem-derived APs must originate not at the surface but in deeper cell layers of the epicotyl. Microelectrode recordings in cortex cells confirm this notion by showing that a shade-induced depolarization indeed precedes the appearance of spikes (Fig.…”

“…1-3) that could serve as the causative generator potential shown in other plants. 11,[33][34] Surface recordings of stem-induced spikes, however, often appear without a preceding depolarization (Figs. 1-3).…”

Light- and dark-induced action potentials inPhyscomitrella patens

“…Light-induced action potentials (APs) are known in excitable plants. [13][14][15][16] Moreover, shade-induced APs were also reported in plants. 17,18 Unexcitable cells respond to illumination or darkening with transient potential changes of relatively low amplitudes which depend on light intensity and quality.…”

Generation of action potential-type changes in response to darkening and illumination as indication of the plasma membrane proton pump status in Marchantia polymorpha

“…Simultaneously, there are reports about intracellular investigations conducted on another liverwort Conocephalum conicum (Dziubińska et al 1983;Favre et al 1999b;Król et al 2007;Zawadzki and Trębacz 1985) and on the moss Physcomitrella patens, a species that is phylogenetically related to liverworts and regarded as a model system in plant functional genomics (Decker et al 2006;Reski 1999) and electrophysiology (Ermolayeva et al 1996(Ermolayeva et al , 1997Koselski et al 2008Koselski et al , 2013Koselski et al , 2015. Conocephalum conicum displays excitability to various stimuli, such as light (Król and Trębacz 1999;Trębacz and Zawadzki 1985;Trębacz et al 1989a), cold (Król et al 2003;Kupisz and Trebacz 2011), wounding (Favre et al 1999a), and direct current (DC) (Dziubińska et al 1983;Król and Trębacz 1999;Paszewski et al 1982). Among the stimuli mentioned above, light signals are considered as environmental factors that play a critical role in growth, reproduction, development, and regeneration, distinguishing liverworts, mosses, and other bryophytes from other plant species (Cove and Ashton 1988).…”