title: Gibberellin regulates PIN-FORMED abundance and is required for auxin transport-dependent growth and development in Arabidopsis thaliana.
abstract: Plants integrate different regulatory signals to control their growth and development. Although a number of physiological observations suggest that there is crosstalk between the phytohormone gibberellin (GA) and auxin, as well as with auxin transport, the molecular basis for this hormonal crosstalk remains largely unexplained. Here, we show that auxin transport is reduced in the inflorescences of Arabidopsis thaliana mutants deficient in GA biosynthesis and signaling. We further show that this reduced auxin transport correlates with a reduction in the abundance of PIN-FORMED (PIN) auxin efflux facilitators in GA-deficient plants and that PIN protein levels recover to wild-type levels following GA treatment. We also demonstrate that the regulation of PIN protein levels cannot be explained by a transcriptional regulation of the PIN genes but that GA deficiency promotes, at least in the case of PIN2, the targeting of PIN proteins for vacuolar degradation. In genetic studies, we reveal that the reduced auxin transport of GA mutants correlates with an impairment in two PIN-dependent growth processes, namely, cotyledon differentiation and root gravitropic responses. Our study thus presents evidence for a role of GA in these growth responses and for a GA-dependent modulation of PIN turnover that may be causative for these differential growth responses.
authors.affiliation: Department of Plant Systems Biology, Center for Life and Food Sciences Weihenstephan, Technische Universität München, 85354 Freising, Germany.
authors.forename: Björn C
authors.initials: BC
authors.lastname: Willige
authors.forename: Erika
authors.initials: E
authors.lastname: Isono
authors.forename: René
authors.initials: R
authors.lastname: Richter
authors.forename: Melina
authors.initials: M
authors.lastname: Zourelidou
authors.forename: Claus
authors.initials: C
authors.lastname: Schwechheimer
mesh_terms: D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D018548:Cotyledon / Q000254:growth & development / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000378:metabolism*; D018522:Gravitropism / Q000502:physiology; D007210:Indoleacetic Acids / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010937:Plant Growth Regulators / Q000378:metabolism; D018517:Plant Roots / Q000033:anatomy & histology / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014158:Transcription, Genetic; D014617:Vacuoles / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D005875:Gibberellins; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; D010937:Plant Growth Regulators; D011993:Recombinant Fusion Proteins; C100794:AUX1 protein, Arabidopsis; C116363:PIN1 protein, Arabidopsis; C117013:AT5G57090 protein, Arabidopsis; C449300:PIN3 protein, Arabidopsis