title: Receptor-mediated increase in cytoplasmic free calcium required for activation of pathogen defense in parsley.
abstract: Transient influx of Ca(2+) constitutes an early element of signaling cascades triggering pathogen defense responses in plant cells. Treatment with the Phytophthora sojae-derived oligopeptide elicitor, Pep-13, of parsley cells stably expressing apoaequorin revealed a rapid increase in cytoplasmic free calcium ([Ca(2+)](cyt)), which peaked at approximately 1 microM and subsequently declined to sustained values of 300 nM. Activation of this biphasic [Ca(2+)](cyt) signature was achieved by elicitor concentrations sufficient to stimulate Ca(2+) influx across the plasma membrane, oxidative burst, and phytoalexin production. Sustained concentrations of [Ca(2+)](cyt) but not the rapidly induced [Ca(2+)](cyt) transient peak are required for activation of defense-associated responses. Modulation by pharmacological effectors of Ca(2+) influx across the plasma membrane or of Ca(2+) release from internal stores suggests that the elicitor-induced sustained increase of [Ca(2+)](cyt) predominantly results from the influx of extracellular Ca(2+). Identical structural features of Pep-13 were found to be essential for receptor binding, increases in [Ca(2+)](cyt), and activation of defense-associated responses. Thus, a receptor-mediated increase in [Ca(2+)](cyt) is causally involved in signaling the activation of pathogen defense in parsley.
authors.affiliation: Department of Stress and Developmental Biology, Institute of Plant Biochemistry, Weinberg 3, D-06120 Halle/Saale, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Blume
authors.forename: T
authors.initials: T
authors.lastname: Nürnberger
authors.forename: N
authors.initials: N
authors.lastname: Nass
authors.forename: D
authors.initials: D
authors.lastname: Scheel
mesh_terms: D000331:Aequorin / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D019661:Apiaceae / Q000166:cytology / Q000187:drug effects / Q000469:parasitology* / Q000502:physiology*; D001059:Apoproteins / Q000235:genetics / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects*; D002138:Calibration; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D006790:Host-Parasite Interactions; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D008163:Luminescent Measurements; D009842:Oligopeptides / Q000737:chemistry / Q000494:pharmacology; D010936:Plant Extracts / Q000096:biosynthesis; D010937:Plant Growth Regulators / Q000737:chemistry / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016897:Respiratory Burst / Q000187:drug effects; D012717:Sesquiterpenes; D013379:Substrate Specificity; D013729:Terpenes; D014170:Transformation, Genetic; D000094162:Phytoalexins
chemical_list: D001059:Apoproteins; D001425:Bacterial Outer Membrane Proteins; D009842:Oligopeptides; D010936:Plant Extracts; D010937:Plant Growth Regulators; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D012717:Sesquiterpenes; D013729:Terpenes; C060014:apoaequorin; C075462:harpin protein, Erwinia amylovora; C087295:HrpZ protein, Pseudomonas syringae; D000331:Aequorin; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium; D000094162:Phytoalexins