title: Plant extracellular ATP signalling by plasma membrane NADPH oxidase and Ca2+ channels.
abstract: Extracellular ATP regulates higher plant growth and adaptation. The signalling events may be unique to higher plants, as they lack animal purinoceptor homologues. Although it is known that plant cytosolic free Ca2+ can be elevated by extracellular ATP, the mechanism is unknown. Here, we have studied roots of Arabidopsis thaliana to determine the events that lead to the transcriptional stress response evoked by extracellular ATP. Root cell protoplasts were used to demonstrate that signalling to elevate cytosolic free Ca2+ is determined by ATP perception at the plasma membrane, and not at the cell wall. Imaging revealed that extracellular ATP causes the production of reactive oxygen species in intact roots, with the plasma membrane NADPH oxidase AtRBOHC being the major contributor. This resulted in the stimulation of plasma membrane Ca2+-permeable channels (determined using patch-clamp electrophysiology), which contribute to the elevation of cytosolic free Ca2+. Disruption of this pathway in the AtrbohC mutant impaired the extracellular ATP-induced increase in reactive oxygen species (ROS), the activation of Ca2+ channels, and the transcription of the MAP kinase3 gene that is known to be involved in stress responses. This study shows that higher plants, although bereft of purinoceptor homologues, could have evolved a distinct mechanism to transduce the ATP signal at the plasma membrane.
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge CB23EA, UK.
authors.forename: Vadim
authors.initials: V
authors.lastname: Demidchik
authors.forename: Zhonglin
authors.initials: Z
authors.lastname: Shang
authors.forename: Ryoung
authors.initials: R
authors.lastname: Shin
authors.forename: Elinor
authors.initials: E
authors.lastname: Thompson
authors.forename: Lourdes
authors.initials: L
authors.lastname: Rubio
authors.forename: Anuphon
authors.initials: A
authors.lastname: Laohavisit
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Mortimer
authors.forename: Stephen
authors.initials: S
authors.lastname: Chivasa
authors.forename: Antoni R
authors.initials: AR
authors.lastname: Slabas
authors.forename: Beverley J
authors.initials: BJ
authors.lastname: Glover
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Schachtman
authors.forename: Sergey N
authors.initials: SN
authors.lastname: Shabala
authors.forename: Julia M
authors.initials: JM
authors.lastname: Davies
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D020013:Calcium Signaling; D002462:Cell Membrane / Q000378:metabolism; D019255:NADPH Oxidases / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D015220:Calcium Channels; D017382:Reactive Oxygen Species; D000255:Adenosine Triphosphate; D019255:NADPH Oxidases; D002118:Calcium