title: Induction of defence gene expression by oligogalacturonic acid requires increases in both cytosolic calcium and hydrogen peroxide in Arabidopsis thaliana.
abstract: Responses to oligogalacturonic acid (OGA) were determined in transgenic Arabidopsis thaliana seedlings expressing the calcium reporter protein aequorin. OGA stimulated a rapid, substantial and transient increase in the concentration of cytosolic calcium ([Ca2+]cyt) that peaked after ca. 15 s. This increase was dose-dependent, saturating at ca. 50 ug Gal equiv/ml of OGA. OGA also stimulated a rapid generation of H2O2. A small, rapid increase in H2O2 content was followed by a much larger oxidative burst, with H2O2 content peaking after ca. 60 min and declining thereafter. Induction of the oxidative burst by OGA was also dose-dependent, with a maximum response again being achieved at ca. 50 ug Gal equiv/mL. Inhibitors of calcium fluxes inhibited both increases in [Ca2+]cyt and [H2O2], whereas inhibitors of NADPH oxidase blocked only the oxidative burst. OGA increased strongly the expression of the defence-related genes CHS, GST, PAL and PR-1. This induction was suppressed by inhibitors of calcium flux or NADPH oxidase, indicating that increases in both cytosolic calcium and H2O2 are required for OGA-induced gene expression.
authors.affiliation: Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
authors.forename: Xiang Yang
authors.initials: XY
authors.lastname: Hu
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Neill
authors.forename: Wei Ming
authors.initials: WM
authors.lastname: Cai
authors.forename: Zhang Cheng
authors.initials: ZC
authors.lastname: Tang
mesh_terms: D000331:Aequorin / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002395:Catecholamines / Q000494:pharmacology; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D017930:Genes, Reporter; D006861:Hydrogen Peroxide / Q000378:metabolism*; D048288:Imidazolines / Q000494:pharmacology; D007811:Lanthanum / Q000494:pharmacology; D009844:Oligosaccharides / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010084:Oxidation-Reduction / Q000187:drug effects; D030821:Plants, Genetically Modified; D011725:Pyridines / Q000494:pharmacology; D012430:Ruthenium Red / Q000494:pharmacology; D036226:Seedlings / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
chemical_list: D002395:Catecholamines; D048288:Imidazolines; D009844:Oligosaccharides; D011725:Pyridines; C412763:oligogalacturonic acid; C028521:lanthanum chloride; D012430:Ruthenium Red; D000331:Aequorin; D004533:Egtazic Acid; D007811:Lanthanum; D006861:Hydrogen Peroxide; C011775:(3,4-dihydroxyphenylamino)-2-imidazoline; C023666:pyridine; D002118:Calcium