title: Overexpression of the gibberellin 2-oxidase gene from Torenia fournieri induces dwarf phenotypes in the liliaceous monocotyledon Tricyrtis sp.
abstract: Gibberellins (GAs) are the plant hormones that control many aspects of plant growth and development, including stem elongation. Genes encoding enzymes related to the GA biosynthetic and metabolic pathway have been isolated and characterized in many plant species. Gibberellin 2-oxidase (GA2ox) catalyzes bioactive GAs or their immediate precursors to inactive forms; therefore, playing a direct role in determining the levels of bioactive GAs. In the present study, we produced transgenic plants of the liliaceous monocotyledon Tricyrtis sp. overexpressing the GA2ox gene from the linderniaceous dicotyledon Torenia fournieri (TfGA2ox2). All six transgenic plants exhibited dwarf phenotypes, and they could be classified into two classes according to the degree of dwarfism: three plants were moderately dwarf and three were severely dwarf. All of the transgenic plants had small or no flowers, and smaller, rounder and darker green leaves. Quantitative real-time reverse transcription-polymerase chain reaction (PCR) analysis showed that the TfGA2ox2 expression level generally correlated with the degree of dwarfism. The endogenous levels of bioactive GAs, GA1 and GA4, largely decreased in transgenic plants as shown by liquid chromatography-mass spectrometry (LC-MS) analysis, and the level also correlated with the degree of dwarfism. Exogenous treatment of transgenic plants with gibberellic acid (GA3) resulted in an increased shoot length, indicating that the GA signaling pathway might normally function in transgenic plants. Thus, morphological changes in transgenic plants may result from a decrease in the endogenous levels of bioactive GAs. Finally, a possibility of molecular breeding for plant form alteration in liliaceous ornamental plants by genetically engineering the GA metabolic pathway is discussed.
authors.affiliation: Faculty of Agriculture, Niigata University, 2-8050 Ikarashi, Niigata 950-2181, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Otani
authors.forename: Shuhei
authors.initials: S
authors.lastname: Meguro
authors.forename: Haruka
authors.initials: H
authors.lastname: Gondaira
authors.forename: Megumi
authors.initials: M
authors.lastname: Hayashi
authors.forename: Misaki
authors.initials: M
authors.lastname: Saito
authors.forename: Dong-Sheng
authors.initials: DS
authors.lastname: Han
authors.forename: Phithak
authors.initials: P
authors.lastname: Inthima
authors.forename: Kanyaratt
authors.initials: K
authors.lastname: Supaibulwatana
authors.forename: Shiro
authors.initials: S
authors.lastname: Mori
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Jikumaru
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kamiya
authors.forename: Tuoping
authors.initials: T
authors.lastname: Li
authors.forename: Tomoya
authors.initials: T
authors.lastname: Niki
authors.forename: Takaaki
authors.initials: T
authors.lastname: Nishijima
authors.forename: Masaji
authors.initials: M
authors.lastname: Koshioka
authors.forename: Masaru
authors.initials: M
authors.lastname: Nakano
mesh_terms: D060054:Agrobacterium / Q000235:genetics; D001947:Breeding; D002853:Chromatography, Liquid; D035264:Flowers / Q000235:genetics / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000008:administration & dosage / Q000378:metabolism; D007564:Japan; D019686:Lamiaceae / Q000235:genetics; D019668:Liliaceae / Q000235:genetics* / Q000254:growth & development*; D013058:Mass Spectrometry; D008855:Microscopy, Electron, Scanning; D006899:Mixed Function Oxygenases / Q000235:genetics* / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development; D016133:Polymerase Chain Reaction; D014170:Transformation, Genetic
chemical_list: D005875:Gibberellins; D010940:Plant Proteins; C007842:gibberellic acid; D006899:Mixed Function Oxygenases; C121463:gibberellin 2-dioxygenase
keywords: CaMV; FW; GA; GA(3); GA20ox; GA2ox; GA3ox; Gibberellin metabolic pathway; HPT; LC–MS; Liliaceous ornamental plant; Morphological alteration; NOS; NPTII; PCR; RT-PCR; SEM; SPAD; Transgenic plant; UNI; cauliflower mosaic virus; fresh weight; gibberellic acid; gibberellin; gibberellin 2-oxidase; gibberellin 20-oxidase; gibberellin 3-oxidase; hygromycin phosphotransferase; liquid chromatography–mass spectrometry; neomycin phosphotransferase II; nopaline synthase; polymerase chain reaction; reverse transcription-polymerase chain reaction; scanning electron microscope; soil and plant analyzer development; uniconazol