title: The vacuolar Ca2+-activated channel TPC1 regulates germination and stomatal movement.
abstract: Cytosolic free calcium ([Ca2+]cyt) is a ubiquitous signalling component in plant cells. Numerous stimuli trigger sustained or transient elevations of [Ca2+]cyt that evoke downstream stimulus-specific responses. Generation of [Ca2+]cyt signals is effected through stimulus-induced opening of Ca2+-permeable ion channels that catalyse a flux of Ca2+ into the cytosol from extracellular or intracellular stores. Many classes of Ca2+ current have been characterized electrophysiologically in plant membranes. However, the identity of the ion channels that underlie these currents has until now remained obscure. Here we show that the TPC1 ('two-pore channel 1') gene of Arabidopsis thaliana encodes a class of Ca2+-dependent Ca2+-release channel that is known from numerous electrophysiological studies as the slow vacuolar channel. Slow vacuolar channels are ubiquitous in plant vacuoles, where they form the dominant conductance at micromolar [Ca2+]cyt. We show that a tpc1 knockout mutant lacks functional slow vacuolar channel activity and is defective in both abscisic acid-induced repression of germination and in the response of stomata to extracellular calcium. These studies unequivocally demonstrate a critical role of intracellular Ca2+-release channels in the physiological processes of plants.
authors.affiliation: Biology Department, Area 9, University of York, PO Box 373, York YO10 5YW, UK.
authors.forename: Edgar
authors.initials: E
authors.lastname: Peiter
authors.forename: Frans J M
authors.initials: FJ
authors.lastname: Maathuis
authors.forename: Lewis N
authors.initials: LN
authors.lastname: Mills
authors.forename: Heather
authors.initials: H
authors.lastname: Knight
authors.forename: Jérôme
authors.initials: J
authors.lastname: Pelloux
authors.forename: Alistair M
authors.initials: AM
authors.lastname: Hetherington
authors.forename: Dale
authors.initials: D
authors.lastname: Sanders
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000254:growth & development / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D002384:Catalysis; D004594:Electrophysiology; D018525:Germination / Q000502:physiology*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D014617:Vacuoles / Q000378:metabolism*; D000097903:Two-Pore Channels
chemical_list: D029681:Arabidopsis Proteins; D002118:Calcium; D015220:Calcium Channels; C498240:TPC1 protein, Arabidopsis; D000097903:Two-Pore Channels