Induction of defence gene expression by oligogalacturonic acid requires increases in both cytosolic calcium and hydrogen peroxide in Arabidopsis thaliana.
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.
Hu
Xiang Yang
XY
Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
Neill
Steven J
SJ
Cai
Wei Ming
WM
Tang
Zhang Cheng
ZC
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
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