title: A RhoGDP dissociation inhibitor spatially regulates growth in root hair cells.
abstract: Root hairs are cellular protuberances extending from the root surface into the soil; there they provide access to immobile inorganic ions such as phosphate, which are essential for growth. Their cylindrical shape results from a polarized mechanism of cell expansion called tip growth in which elongation is restricted to a small area at the surface of the hair-forming cell (trichoblast) tip. Here we identify proteins that spatially control the sites at which cell growth occurs by isolating Arabidopsis mutants (scn1) that develop ectopic sites of growth on trichoblasts. We cloned SCN1 and showed that SCN1 is a RhoGTPase GDP dissociation inhibitor (RhoGDI) that spatially restricts the sites of growth to a single point on the trichoblast. We showed previously that localized production of reactive oxygen species by RHD2/AtrbohC NADPH oxidase is required for hair growth; here we show that SCN1/AtrhoGDI1 is a component of the mechanism that focuses RHD2/AtrbohC-catalysed production of reactive oxygen species to hair tips during wild-type development. We propose that the spatial organization of growth in plant cells requires the local RhoGDI-regulated activation of the RHD2/AtrbohC NADPH oxidase.
authors.affiliation: Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, UK.
authors.forename: Rachel J
authors.initials: RJ
authors.lastname: Carol
authors.forename: Seiji
authors.initials: S
authors.lastname: Takeda
authors.forename: Paul
authors.initials: P
authors.lastname: Linstead
authors.forename: Marcus C
authors.initials: MC
authors.lastname: Durrant
authors.forename: Hana
authors.initials: H
authors.lastname: Kakesova
authors.forename: Paul
authors.initials: P
authors.lastname: Derbyshire
authors.forename: Sinéad
authors.initials: S
authors.lastname: Drea
authors.forename: Viktor
authors.initials: V
authors.lastname: Zarsky
authors.forename: Liam
authors.initials: L
authors.lastname: Dolan
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009024:Morphogenesis; D009154:Mutation / Q000235:genetics; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D018517:Plant Roots / Q000166:cytology* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013489:Suppression, Genetic / Q000235:genetics; D020741:rho GTP-Binding Proteins / Q000378:metabolism; D062948:rho Guanine Nucleotide Dissociation Inhibitor alpha; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors
chemical_list: C569638:ARHGDIA protein, human; D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; D020730:Guanine Nucleotide Dissociation Inhibitors; D017382:Reactive Oxygen Species; C506817:SCN1 protein, Arabidopsis; D062948:rho Guanine Nucleotide Dissociation Inhibitor alpha; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; C473291:Rhd2 protein, Arabidopsis; D019255:NADPH Oxidases; D020741:rho GTP-Binding Proteins