title: Gibberellins inhibit adventitious rooting in hybrid aspen and Arabidopsis by affecting auxin transport.
abstract: Knowledge of processes involved in adventitious rooting is important to improve both fundamental understanding of plant physiology and the propagation of numerous plants. Hybrid aspen (Populus tremula × tremuloïdes) plants overexpressing a key gibberellin (GA) biosynthesis gene (AtGA20ox1) grow rapidly but have poor rooting efficiency, which restricts their clonal propagation. Therefore, we investigated the molecular basis of adventitious rooting in Populus and the model plant Arabidopsis. The production of adventitious roots (ARs) in tree cuttings is initiated from the basal stem region, and involves the interplay of several endogenous and exogenous factors. The roles of several hormones in this process have been characterized, but the effects of GAs have not been fully investigated. Here, we show that a GA treatment negatively affects the numbers of ARs produced by wild-type hybrid aspen cuttings. Furthermore, both hybrid aspen plants and intact Arabidopsis seedlings overexpressing AtGA20ox1, PttGID1.1 or PttGID1.3 genes (with a 35S promoter) produce few ARs, although ARs develop from the basal stem region of hybrid aspen and the hypocotyl of Arabidopsis. In Arabidopsis, auxin and strigolactones are known to affect AR formation. Our data show that the inhibitory effect of GA treatment on adventitious rooting is not mediated by perturbation of the auxin signalling pathway, or of the strigolactone biosynthetic and signalling pathways. Instead, GAs appear to act by perturbing polar auxin transport, in particular auxin efflux in hybrid aspen, and both efflux and influx in Arabidopsis.
authors.affiliation: Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 87, Umeå, Sweden; Institut National de la Recherche Agronomique, UMR 1202 BIOGECO, 69 route d'Arcachon, F-33612, Cestas Cedex, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Mauriat
authors.forename: Anna
authors.initials: A
authors.lastname: Petterle
authors.forename: Catherine
authors.initials: C
authors.lastname: Bellini
authors.forename: Thomas
authors.initials: T
authors.lastname: Moritz
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport / Q000235:genetics / Q000502:physiology; D002678:Chimera; D003517:Cyclopentanes / Q000378:metabolism / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000378:metabolism* / Q000494:pharmacology; D018546:Hypocotyl / Q000235:genetics; D007210:Indoleacetic Acids / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism; D054883:Oxylipins / Q000378:metabolism / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D030821:Plants, Genetically Modified; D032107:Populus / Q000235:genetics / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D005875:Gibberellins; D007210:Indoleacetic Acids; C470445:MAX1 protein, Arabidopsis; D054883:Oxylipins; C011006:jasmonic acid; D006899:Mixed Function Oxygenases; C475746:MAX4 protein, Arabidopsis; D010105:Oxygenases
keywords: Arabidopsis; Populus; adventitious roots; auxin; auxin transport; gibberellins; jasmonate