title: The gene MACCHI-BOU 4/ENHANCER OF PINOID encodes a NPH3-like protein and reveals similarities between organogenesis and phototropism at the molecular level.
abstract: Intercellular transport of the phytohormone auxin is a significant factor for plant organogenesis. To investigate molecular mechanisms by which auxin controls organogenesis, we analyzed the macchi-bou 4 (mab4) mutant identified as an enhancer of pinoid (pid). Although mab4 and pid single mutants displayed relatively mild cotyledon phenotypes, pid mab4 double mutants completely lacked cotyledons. We found that MAB4 was identical to ENHANCER OF PINOID (ENP), which has been suggested to control PIN1 polarity in cotyledon primordia. MAB4/ENP encodes a novel protein, which belongs to the NON-PHOTOTROPIC HYPOCOTYL 3 (NPH3) family thought to function as a signal transducer in phototropism and control lateral translocation of auxin. MAB4/ENP mRNA was detected in the protodermal cell layer of the embryo and the meristem L1 layer at the site of organ initiation. In the mab4 embryo, the abundance of PIN1:GFP was severely decreased at the plasma membrane in the protodermal cell layer. In addition, subcellular localization analyses indicated that MAB4/ENP resides on a subpopulation of endosomes as well as on unidentified intracellular compartments. These results indicate that MAB4/ENP is involved in polar auxin transport in organogenesis.
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara 630-0101, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Furutani
authors.forename: Takahito
authors.initials: T
authors.lastname: Kajiwara
authors.forename: Takehide
authors.initials: T
authors.lastname: Kato
authors.forename: Birgit S
authors.initials: BS
authors.lastname: Treml
authors.forename: Christine
authors.initials: C
authors.lastname: Stockum
authors.forename: Ramón A
authors.initials: RA
authors.lastname: Torres-Ruiz
authors.forename: Masao
authors.initials: M
authors.lastname: Tasaka
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D017930:Genes, Reporter / Q000235:genetics; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D018524:Phototropism; D010802:Phylogeny; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D029681:Arabidopsis Proteins; C508612:Enhancer of Pinoid protein, Arabidopsis; D026901:Membrane Transport Proteins; C400222:NPH3 protein, Arabidopsis; C469261:a bout de souffle protein, Arabidopsis