A nitrate-permeable ion channel in the tonoplast of the moss Physcomitrella patens

Abstract

Main conclusion In this work, for the first time the activity of nitrate-permeable channels in the tonoplast of the moss Physcomitrella patens was recorded. The channels allowed nitrate flow in one direction-from the cytoplasm to the vacuole. Selectivity of nitrate over chloride of the channels was proved. The activity of the channels was dependent on cytoplasmic calcium, magnesium, and pH.A patch-clamp study carried out on the vacuolar membrane of the moss Physcomitrella patens has revealed that inhibition of cation-selective channels leads to disclosure of channels permeable to NO 3 -. These channels were inwardly rectifying and allowed anions to flow from the cytoplasm to the vacuole. After a decrease in the cytoplasmic NO 3 -concentration, the current density recorded in the whole-vacuole configuration and amplitude of the currents flowing through single channels were reduced. Application of the NO 3 -gradient caused a shift in the reversal potential (E rev ) towards E NO3-, indicating NO 3 -permeability. Research of the selectivity of the channels to Cl -and NO 3 -was also done; it indicated that Cl -is less permeable than NO 3 -(P NO3 /P Cl = 3.08). Measurements with different concentrations of cytoplasmic Ca 2? and Mg 2? revealed that the channel was activated by different concentrations of these ions-100 lM Ca 2? and 10 mM Mg 2? . Calcium dependence of the channels was also modulated by a redox agent-DTT (dithiothreitol), which added on the cytoplasmic side, caused a reduction in the threshold of channel activation with cytoplasmic Ca 2? . The NO 3 -permeable channel was also pH dependent. A decrease in the cytoplasmic pH reduced the open probability of the channel; in turn, an increase in the vacuolar pH did not decrease ion channel activity but lowered its conductance.

The role of vacuolar ion channels in salt stress tolerance in the liverwort Conocephalum conicum

“…Currents carried by K + and Mg 2+ were recorded in earlier patch-clamp studies of SV channels in C. conicum (Trębacz et al 2007;Trębacz and Schӧnknecht 2000), although sodium permeability and their possible role in salt stress have not been addressed. SV-type currents were also recorded in plants closely related with Conocephalum-the liverwort Marchantia polymorpha [K + currents; (Koselski et al 2017)] and the moss Physcomitrella patens [Na + , K + , Mg 2+ and Ca 2+ currents; (Koselski et al 2013(Koselski et al , 2015]. Another important feature of SV channels is their calcium dependence.…”

Osmotic and Salt Stresses Modulate Spontaneous and Glutamate-Induced Action Potentials and Distinguish between Growth and Circumnutation in Helianthus annuus Seedlings

“…In plants, SAPs were described over 20 years ago by Zawadzki et al ( 1995 ) in H. annuus and lately they have been observed in Solanum lycopersicum plants (Macedo et al, 2015 ). The AP ion mechanism in plants has been elaborated in many species, for example C. conicum, Arabidopsis thaliana , and Physcomytrella patens (Trebacz and Zawadzki, 1985 ; Trebacz et al, 1989 , 1994 , 2007 ; Trebacz, 1992 ; Krol et al, 2006 , 2007 ; Koselski et al, 2015 , 2017 ). Fundamental players in the AP ion mechanism in plants are H + , Ca 2+ , K + , and Cl − .…”

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

“…However, to date, there has been no report about the characteristics of electrical signals in M. polymorpha gamethophyte cells. 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).…”