title: Cation channels are involved in brassinosteroid signalling in higher plants.
abstract: Brassinosteroids (BRs) are an important class of plant hormones with a multitude of functions. They have been intensively investigated for their biosynthesis, distribution and physiological functions. The aim of this study was to examine possible effects of BRs on the plant plasma membrane cation conductances and Ca(2+) signalling. The wheat root protoplasts (tested by patch-clamping) and excised arabidopsis roots (analysed by Ca(2+)-aequorin chemiluminometry), were used. In the whole-cell plasma membrane patches, 24-epibrassinolide, 28-homobrassionolide or 24-epicastasterone (1 μM) were applied exogenously. 24-Epicastasterone increased the activity of the K(+) efflux conductance in 50% of tested protoplasts while 24-epibrassonolide and 28-homobrassionolide did not modify the plasma membrane currents. Addition of 24-epicastasterone at the cytosolic side (to the pipette solution) resulted in dramatic stimulation of a time-dependent K(+) efflux current (in 30% of protoplasts) and an activation of Ca(2+) influx currents (in 30% of protoplasts). Gadolinium ions, which are blockers of cation channels, inhibited the 24-epicastasterone-induced cation channel activities. In Arabidopsis thaliana plants constitutively expressing aequorin, exogenous 24-epibrassonolide, 28-homobrassionolide and 24-epicastasterone induced a transient elevation of the cytosolic free Ca(2+), which was inhibited by Gd(3+) and mediated by Ca(2+) influx from the bathing solution. In Ca(2+)-aequorin tests, 10 μM of exogenous BRs was the minimal concentration at which statistically significant changes of the cytosolic Ca(2+) were observed. In conclusion, the obtained results suggest that the plasma membrane of root cells contains the brassinosteroid-activated cation-permeable channels, which can probably be involved in rapid regulation of the K(+) homeostasis and Ca(2+) signalling.
authors.affiliation: Department of Plant Cell Biology and Bioengineering, Biological Faculty, Belarusian State University, 4 Independence Ave., Minsk 220030, Belarus. Electronic address: streltsovadasha@tut.by.
authors.forename: Darya
authors.initials: D
authors.lastname: Straltsova
authors.affiliation: Department of Plant Cell Biology and Bioengineering, Biological Faculty, Belarusian State University, 4 Independence Ave., Minsk 220030, Belarus. Electronic address: polinachikun@gmail.com.
authors.forename: Palina
authors.initials: P
authors.lastname: Chykun
authors.affiliation: School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, United Kingdom. Electronic address: ssubraa@essex.ac.uk.
authors.forename: Sunitha
authors.initials: S
authors.lastname: Subramaniam
authors.affiliation: School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, United Kingdom. Electronic address: asosan@essex.ac.uk.
authors.forename: Arifa
authors.initials: A
authors.lastname: Sosan
authors.affiliation: Department of Plant Cell Biology and Bioengineering, Biological Faculty, Belarusian State University, 4 Independence Ave., Minsk 220030, Belarus. Electronic address: dmitry-kolbanov@tut.by.
authors.forename: Dmitriy
authors.initials: D
authors.lastname: Kolbanov
authors.affiliation: Department of Plant Cell Biology and Bioengineering, Biological Faculty, Belarusian State University, 4 Independence Ave., Minsk 220030, Belarus. Electronic address: sokolik@bsu.by.
authors.forename: Anatoliy
authors.initials: A
authors.lastname: Sokolik
authors.affiliation: Department of Plant Cell Biology and Bioengineering, Biological Faculty, Belarusian State University, 4 Independence Ave., Minsk 220030, Belarus. Electronic address: dzemidchyk@bsu.by.
authors.forename: Vadim
authors.initials: V
authors.lastname: Demidchik
mesh_terms: D060406:Brassinosteroids / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism*; D015398:Signal Transduction; D014908:Triticum / Q000378:metabolism*
chemical_list: D060406:Brassinosteroids; D015220:Calcium Channels; D015221:Potassium Channels
keywords: Arabidopsis; Brassinosteroids; Calcium; Epicastasterone; Ion channels; Potassium