title: Multiple loss-of-function of Arabidopsis gibberellin receptor AtGID1s completely shuts down a gibberellin signal.
abstract: Arabidopsis carries three receptor genes for the phytohormone gibberellin (GA), AtGID1a, AtGID1b and AtGID1c. Expression of each gene in the rice gid1-1 mutant for GA receptors causes reversion of its severely dwarfed phenotype and GA insensitivity to a normal level, even though each loss-of-function mutant shows no clear phenotype in Arabidopsis (Nakajima et al., 2006). In this paper, we report the functional redundancy and specificity of each AtGID1 by analyzing the multiple mutants for loss of function. Seeds of the double knockout mutants atgid1a atgid1b, atgid1a atgid1c and atgid1b atgid1c germinated normally. The double knockout mutant atgid1a atgid1c showed a dwarf phenotype, while other double mutants were of normal height compared to the wild-type. The stamens of the double knockout mutant atgid1a atgid1b were significantly shorter than those of the wild-type, and this leads to low fertility. A severe disarrangement of the pattern on its seed surface was also observed. The triple knockout mutant atgid1a atgid1b atgid1c did not germinate voluntarily, and only started to grow when the seed coat was peeled off after soaking. Seedlings of the triple knockout mutants were severe dwarfs, only a few millimeters high after growing for 1 month. Moreover, the triple knockout seedlings completely lost their ability to respond to exogenously applied GA. These results show that all AtGID1s function as GA receptors in Arabidopsis, but have specific role(s) for growth and development.
authors.affiliation: BioResource Center, RIKEN, Tsukuba, Ibaraki 305-0074, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Iuchi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Suzuki
authors.forename: Young-Cheon
authors.initials: YC
authors.lastname: Kim
authors.forename: Atsuko
authors.initials: A
authors.lastname: Iuchi
authors.forename: Takashi
authors.initials: T
authors.lastname: Kuromori
authors.forename: Miyako
authors.initials: M
authors.lastname: Ueguchi-Tanaka
authors.forename: Tadao
authors.initials: T
authors.lastname: Asami
authors.forename: Isomaro
authors.initials: I
authors.lastname: Yamaguchi
authors.forename: Makoto
authors.initials: M
authors.lastname: Matsuoka
authors.forename: Masatomo
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Nakajima
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial; D018525:Germination / Q000502:physiology; D005875:Gibberellins / Q000378:metabolism*; D016254:Mutagenesis, Insertional; D010641:Phenotype; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; C512225:GID1a protein, Arabidopsis; C512226:GID1b protein, Arabidopsis; C512227:GID1c protein, Arabidopsis; D005875:Gibberellins; D011956:Receptors, Cell Surface; C036483:T-DNA