title: Reactive oxygen species produced by NADPH oxidase regulate plant cell growth.
abstract: Cell expansion is a central process in plant morphogenesis, and the elongation of roots and root hairs is essential for uptake of minerals and water from the soil. Ca2+ influx from the extracellular store is required for (and sets the rates of) cell elongation in roots. Arabidopsis thaliana rhd2 mutants are defective in Ca2+ uptake and consequently cell expansion is compromised--rhd2 mutants have short root hairs and stunted roots. To determine the regulation of Ca2+ acquisition in growing root cells we show here that RHD2 is an NADPH oxidase, a protein that transfers electrons from NADPH to an electron acceptor leading to the formation of reactive oxygen species (ROS). We show that ROS accumulate in growing wild-type (WT) root hairs but their levels are markedly decreased in rhd2 mutants. Blocking the activity of the NADPH oxidase with diphenylene iodonium (DPI) inhibits ROS formation and phenocopies Rhd2-. Treatment of rhd2 roots with ROS partly suppresses the mutant phenotype and stimulates the activity of plasma membrane hyperpolarization-activated Ca2+ channels, the predominant root Ca2+ acquisition system. This indicates that NADPH oxidases control development by making ROS that regulate plant cell expansion through the activation of Ca2+ channels.
authors.affiliation: Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, UK.
authors.forename: Julia
authors.initials: J
authors.lastname: Foreman
authors.forename: Vadim
authors.initials: V
authors.lastname: Demidchik
authors.forename: John H F
authors.initials: JH
authors.lastname: Bothwell
authors.forename: Panagiota
authors.initials: P
authors.lastname: Mylona
authors.forename: Henk
authors.initials: H
authors.lastname: Miedema
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Torres
authors.forename: Paul
authors.initials: P
authors.lastname: Linstead
authors.forename: Silvia
authors.initials: S
authors.lastname: Costa
authors.forename: Colin
authors.initials: C
authors.lastname: Brownlee
authors.forename: Jonathan D G
authors.initials: JD
authors.lastname: Jones
authors.forename: Julia M
authors.initials: JM
authors.lastname: Davies
authors.forename: Liam
authors.initials: L
authors.lastname: Dolan
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000166:cytology* / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling; D002455:Cell Division; D004594:Electrophysiology; D017343:Genes, Plant / Q000235:genetics; D017403:In Situ Hybridization; D009154:Mutation / Q000235:genetics; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D015220:Calcium Channels; D017382:Reactive Oxygen Species; C473291:Rhd2 protein, Arabidopsis; D019255:NADPH Oxidases; D002118:Calcium