title: Strigolactone Inhibition of Branching Independent of Polar Auxin Transport.
abstract: The outgrowth of axillary buds into branches is regulated systemically via plant hormones and the demand of growing shoot tips for sugars. The plant hormone auxin is thought to act via two mechanisms. One mechanism involves auxin regulation of systemic signals, cytokinins and strigolactones, which can move into axillary buds. The other involves suppression of auxin transport/canalization from axillary buds into the main stem and is enhanced by a low sink for auxin in the stem. In this theory, the relative ability of the buds and stem to transport auxin controls bud outgrowth. Here, we evaluate whether auxin transport is required or regulated during bud outgrowth in pea (Pisum sativum). The profound, systemic, and long-term effects of the auxin transport inhibitor N-1-naphthylphthalamic acid had very little inhibitory effect on bud outgrowth in strigolactone-deficient mutants. Strigolactones can also inhibit bud outgrowth in N-1-naphthylphthalamic acid-treated shoots that have greatly diminished auxin transport. Moreover, strigolactones can inhibit bud outgrowth despite a much diminished auxin supply in in vitro or decapitated plants. These findings demonstrate that auxin sink strength in the stem is not important for bud outgrowth in pea. Consistent with alternative mechanisms of auxin regulation of systemic signals, enhanced auxin biosynthesis in Arabidopsis (Arabidopsis thaliana) can suppress branching in yucca1D plants compared with wild-type plants, but has no effect on bud outgrowth in a strigolactone-deficient mutant background.
authors.affiliation: The University of Queensland, School of Biological Sciences, St. Lucia, Queensland 4072, Australia.
authors.forename: Philip B
authors.identifier: http://orcid.org/0000-0003-4871-9260
authors.initials: PB
authors.lastname: Brewer
authors.affiliation: The University of Queensland, School of Biological Sciences, St. Lucia, Queensland 4072, Australia.
authors.forename: Elizabeth A
authors.identifier: http://orcid.org/0000-0003-4068-0349
authors.initials: EA
authors.lastname: Dun
authors.affiliation: The University of Queensland, School of Biological Sciences, St. Lucia, Queensland 4072, Australia.
authors.forename: Renyi
authors.identifier: http://orcid.org/0000-0003-3098-2861
authors.initials: R
authors.lastname: Gui
authors.affiliation: The University of Queensland, School of Biological Sciences, St. Lucia, Queensland 4072, Australia.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Mason
authors.affiliation: The University of Queensland, School of Biological Sciences, St. Lucia, Queensland 4072, Australia c.beveridge@uq.edu.au.
authors.forename: Christine A
authors.initials: CA
authors.lastname: Beveridge
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D007210:Indoleacetic Acids / Q000378:metabolism*; D007783:Lactones / Q000494:pharmacology*; D018519:Meristem / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D018532:Pisum sativum / Q000235:genetics / Q000378:metabolism*; D010797:Phthalimides / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000494:pharmacology; D018520:Plant Shoots / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014316:Tritium / Q000378:metabolism
chemical_list: C507382:GR24 compound; D007210:Indoleacetic Acids; D007783:Lactones; D010797:Phthalimides; D010937:Plant Growth Regulators; D014316:Tritium; C002687:alpha-naphthylphthalamic acid