Reactive oxygen species produced by NADPH oxidase regulate plant cell growth.
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.
Foreman
Julia
J
Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, UK.
Demidchik
Vadim
V
Bothwell
John H F
JH
Mylona
Panagiota
P
Miedema
Henk
H
Torres
Miguel Angel
MA
Linstead
Paul
P
Costa
Silvia
S
Brownlee
Colin
C
Jones
Jonathan D G
JD
Davies
Julia M
JM
Dolan
Liam
L
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*
D029681:Arabidopsis Proteins; D015220:Calcium Channels; D017382:Reactive Oxygen Species; C473291:Rhd2 protein, Arabidopsis; D019255:NADPH Oxidases; D002118:Calcium