title: The RPM1 plant disease resistance gene facilitates a rapid and sustained increase in cytosolic calcium that is necessary for the oxidative burst and hypersensitive cell death.
abstract: Early events occurring during the hypersensitive resistance response (HR) were examined using the avrRpm1/RPM1 gene-for-gene interaction in Arabidopsis challenged by Pseudomonas syringae pv. tomato. Increases in cytosolic Ca2+ were measured in whole leaves using aequorin-mediated bioluminescence. During the HR a sustained increase in Ca2+ was observed which was dependent on the presence of both a functional RPM1 gene product and delivery of the cognate avirulence gene product AvrRpm1. The sequence-unrelated avirulence gene avrB, which also interacts with RPM1, generated a significantly later but similarly prolonged increase in cytosolic Ca2+. Accumulation of H2O2 at reaction sites, as revealed by electron microscopy, occurred within the same time frame as the changes in cytosolic Ca2+. The NADPH oxidase inhibitor diphenylene iodonium chloride did not affect the calcium signature, but did block H2O2 accumulation and the HR. By contrast, the calcium-channel blocker LaCl3 suppressed the increase in cytosolic Ca2+ as well as H2O2 accumulation and the HR, placing calcium elevation upstream of the oxidative burst.
authors.affiliation: Department of Biological Sciences, Wye College, Wye, Kent TN25 5AH, UK. m.grant@wye.ac.uk
authors.forename: M
authors.initials: M
authors.lastname: Grant
authors.forename: I
authors.initials: I
authors.lastname: Brown
authors.forename: S
authors.initials: S
authors.lastname: Adams
authors.forename: M
authors.initials: M
authors.lastname: Knight
authors.forename: A
authors.initials: A
authors.lastname: Ainslie
authors.forename: J
authors.initials: J
authors.lastname: Mansfield
mesh_terms: D000331:Aequorin; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D020013:Calcium Signaling; D016923:Cell Death; D003600:Cytosol / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000378:metabolism; D007811:Lanthanum / Q000494:pharmacology; D008163:Luminescent Measurements; D008854:Microscopy, Electron; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors; D009861:Onium Compounds / Q000494:pharmacology; D010101:Oxygen Consumption; D010935:Plant Diseases / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011549:Pseudomonas / Q000472:pathogenicity*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C100931:AvrB protein, Pseudomonas syringae; D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D009861:Onium Compounds; D010940:Plant Proteins; C095014:RPM1 protein, Arabidopsis; D017382:Reactive Oxygen Species; C028521:lanthanum chloride; D000331:Aequorin; C007517:diphenyleneiodonium; D007811:Lanthanum; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases