title: Hormonal regulation of lateral root development in Arabidopsis modulated by MIZ1 and requirement of GNOM activity for MIZ1 function.
abstract: Plant organ development is important for adaptation to a changing environment. Genetic and physiological studies have revealed that plant hormones play key roles in lateral root formation. In this study, we show that MIZU-KUSSEI1 (MIZ1), which was identified originally as a regulator of hydrotropism, functions as a novel regulator of hormonally mediated lateral root development. Overexpression of MIZ1 (MIZ1OE) in roots resulted in a reduced number of lateral roots being formed; however, this defect could be recovered with the application of auxin. Indole-3-acetic acid quantification analyses showed that free indole-3-acetic acid levels decreased in MIZ1OE roots, which indicates that alteration of auxin level is critical for the inhibition of lateral root formation in MIZ1OE plants. In addition, MIZ1 negatively regulates cytokinin sensitivity on root development. Application of cytokinin strongly induced the localization of MIZ1-green fluorescent protein to lateral root primordia, which suggests that the inhibition of lateral root development by MIZ1 occurs downstream of cytokinin signaling. Surprisingly, miz2, a weak allele of gnom, suppressed developmental defects in MIZ1OE plants. Taken together, these results suggest that MIZ1 plays a role in lateral root development by maintaining auxin levels and that its function requires GNOM activity. These data provide a molecular framework for auxin-dependent organ development in Arabidopsis (Arabidopsis thaliana).
authors.affiliation: Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Miyagi, Japan.
authors.forename: Teppei
authors.initials: T
authors.lastname: Moriwaki
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Miyazawa
authors.forename: Akie
authors.initials: A
authors.lastname: Kobayashi
authors.forename: Mayumi
authors.initials: M
authors.lastname: Uchida
authors.forename: Chiaki
authors.initials: C
authors.lastname: Watanabe
authors.forename: Nobuharu
authors.initials: N
authors.lastname: Fujii
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Takahashi
mesh_terms: D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D003583:Cytokinins / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D016153:Genes, Suppressor; D049452:Green Fluorescent Proteins / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development*; D011993:Recombinant Fusion Proteins / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D003583:Cytokinins; C088087:GNOM protein, Arabidopsis; D020662:Guanine Nucleotide Exchange Factors; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; C116363:PIN1 protein, Arabidopsis; D010937:Plant Growth Regulators; D011993:Recombinant Fusion Proteins; C519512:mizu-kussei1 protein, Arabidopsis; D049452:Green Fluorescent Proteins