title: SCARFACE encodes an ARF-GAP that is required for normal auxin efflux and vein patterning in Arabidopsis.
abstract: To identify molecular mechanisms controlling vein patterns, we analyzed scarface (sfc) mutants. sfc cotyledon and leaf veins are largely fragmented, unlike the interconnected networks in wild-type plants. SFC encodes an ADP ribosylation factor GTPase activating protein (ARF-GAP), a class with well-established roles in vesicle trafficking regulation. Quadruple mutants of SCF and three homologs (ARF-GAP DOMAIN1, 2, and 4) showed a modestly enhanced vascular phenotype. Genetic interactions between sfc and pinoid and between sfc and gnom suggest a possible function for SFC in trafficking of auxin efflux regulators. Genetic analyses also revealed interaction with cotyledon vascular pattern2, suggesting that lipid-based signals may underlie some SFC ARF-GAP functions. To assess possible roles for SFC in auxin transport, we analyzed sfc roots, which showed exaggerated responses to exogenous auxin and higher auxin transport capacity. To determine whether PIN1 intracellular trafficking was affected, we analyzed PIN1:green fluorescent protein (GFP) dynamics using confocal microscopy in sfc roots. We found normal PIN1:GFP localization at the apical membrane of root cells, but treatment with brefeldin A resulted in PIN1 accumulating in smaller and more numerous compartments than in the wild type. These data suggest that SFC is required for normal intracellular transport of PIN1 from the plasma membrane to the endosome.
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, Utah, 84112, USA. sieburth@biology.utah.edu
authors.forename: Leslie E
authors.initials: LE
authors.lastname: Sieburth
authors.forename: Gloria K
authors.initials: GK
authors.lastname: Muday
authors.forename: Edward J
authors.initials: EJ
authors.lastname: King
authors.forename: Geoff
authors.initials: G
authors.lastname: Benton
authors.forename: Sun
authors.initials: S
authors.lastname: Kim
authors.forename: Kasee E
authors.initials: KE
authors.lastname: Metcalf
authors.forename: Lindsay
authors.initials: L
authors.lastname: Meyers
authors.forename: Emylie
authors.initials: E
authors.lastname: Seamen
authors.forename: Jaimie M
authors.initials: JM
authors.lastname: Van Norman
mesh_terms: D020727:ADP-Ribosylation Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000033:anatomy & histology / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D018548:Cotyledon / Q000166:cytology; D020690:GTPase-Activating Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D007210:Indoleacetic Acids / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D018515:Plant Leaves / Q000166:cytology / Q000502:physiology*; D018517:Plant Roots / Q000166:cytology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D020690:GTPase-Activating Proteins; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; C116363:PIN1 protein, Arabidopsis; D012333:RNA, Messenger; C504534:VAN3 protein, Arabidopsis; D020727:ADP-Ribosylation Factors