Strigolactones enhance competition between shoot branches by dampening auxin transport

Scott Crawford, Naoki Shinohara, Tobias Sieberer, Lisa Williamson, Gilu George, Jo Hepworth, Dörte Müller, Malgorzata A Domagalska, Ottoline Leyser

Research output: Contribution to journalA1: Web of Science-articlepeer-review


Strigolactones (SLs), or their derivatives, were recently demonstrated to act as endogenous shoot branching inhibitors, but their biosynthesis and mechanism of action are poorly understood. Here we show that the branching phenotype of mutants in the Arabidopsis P450 family member, MAX1, can be fully rescued by strigolactone addition, suggesting that MAX1 acts in SL synthesis. We demonstrate that SLs modulate polar auxin transport to control branching and that both the synthetic SL GR24 and endogenous SL synthesis significantly reduce the basipetal transport of a second branch-regulating hormone, auxin. Importantly, GR24 inhibits branching only in the presence of auxin in the main stem, and enhances competition between two branches on a common stem. Together, these results support two current hypotheses: that auxin moving down the main stem inhibits branch activity by preventing the establishment of auxin transport out of axillary branches; and that SLs act by dampening auxin transport, thus enhancing competition between branches.

Original languageEnglish
Issue number17
Pages (from-to)2905-13
Number of pages9
Publication statusPublished - 2010
Externally publishedYes


  • Arabidopsis
  • Arabidopsis Proteins
  • Base Sequence
  • Biological Transport, Active
  • DNA Primers
  • Genes, Plant
  • Indoleacetic Acids
  • Lactones
  • Membrane Transport Proteins
  • Mutation
  • Phenotype
  • Plant Growth Regulators
  • Plant Shoots
  • Plants, Genetically Modified
  • Xylem
  • Journal Article
  • Research Support, Non-U.S. Gov't


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