title: Receptor-like activity evoked by extracellular ADP in Arabidopsis root epidermal plasma membrane.
abstract: Extracellular purine nucleotides are implicated in the control of plant development and stress responses. While extracellular ATP is known to activate transcriptional pathways via plasma membrane (PM) NADPH oxidase and calcium channel activation, very little is known about signal transduction by extracellular ADP. Here, extracellular ADP was found to activate net Ca(2+) influx in roots of Arabidopsis (Arabidopsis thaliana) and transiently elevate cytosolic free Ca(2+) in root epidermal protoplasts. An inward Ca(2+)-permeable conductance in root epidermal PM was activated within 1 s of ADP application and repeated application evoked a smaller current. Such response speed and densitization are consistent with operation of equivalents to animal ionotropic purine receptors, although to date no equivalent genes for such receptors have been identified in higher plants. In contrast to ATP, extracellular ADP did not evoke accumulation of intracellular reactive oxygen species. While high concentrations of ATP caused net Ca(2+) efflux from roots, equivalent concentrations of ADP caused net influx. Overall the results point to a discrete ADP signaling pathway, reliant on receptor-like activity at the PM.
authors.affiliation: Department of Biology, University of Essex, Colchester CO4 3SQ, United Kingdom.
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: Renato
authors.initials: R
authors.lastname: Colaço
authors.forename: Anuphon
authors.initials: A
authors.lastname: Laohavisit
authors.forename: Sergey
authors.initials: S
authors.lastname: Shabala
authors.forename: Julia M
authors.initials: JM
authors.lastname: Davies
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism*; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D015640:Ion Channel Gating / Q000187:drug effects; D019441:Plant Epidermis / Q000187:drug effects / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D011523:Protoplasts / Q000187:drug effects / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*
chemical_list: D017382:Reactive Oxygen Species; D011956:Receptors, Cell Surface; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D011188:Potassium; D002118:Calcium