title: Knockdown of strigolactone biosynthesis genes in Populus affects BRANCHED1 expression and shoot architecture.
abstract: Plant architecture is modified by a regulatory system that controls axillary bud outgrowth. Key components in this system are strigolactones (SLs) and BRANCHED1, which inhibit bud outgrowth. Their role has been described in herbaceous model systems, including Arabidopsis, rice and pea. However, a role in woody perennial species, including the model tree poplar, has not been unequivocally proven. In this study, we tested a role for SLs in Populus × canescens by treatment with the synthetic SL GR24. We generated MORE AXILLARY BRANCHING4 (MAX4) knockdown lines to study the architectural phenotype of poplar SL biosynthesis mutants and the expression of SL-regulated genes. We show that GR24 is perceived by the model tree poplar. MAX4 knockdown lines exhibit typical SL deficiency symptoms. The observed changes in branching pattern, internode length and plant height can be rescued by grafting. We identified putative poplar BRANCHED1 and BRANCHED2 genes and provide evidence for a regulation of BRANCHED1 by SLs. Our results suggest a conservation of major regulatory mechanisms in bud outgrowth control in the model tree poplar. This may facilitate further research, pinpointing the role of SLs and BRANCHED1 in the complex regulation of bud outgrowth in trees.
authors.affiliation: Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, Göttingen, 37077, Germany.
authors.forename: Merlin
authors.initials: M
authors.lastname: Muhr
authors.affiliation: Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, Göttingen, 37077, Germany.
authors.forename: Nele
authors.initials: N
authors.lastname: Prüfer
authors.affiliation: Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, Göttingen, 37077, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Paulat
authors.affiliation: Department of Plant Cell Biology, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, Göttingen, 37077, Germany. tteichm@gwdg.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Teichmann
mesh_terms: D053898:Biosynthetic Pathways / Q000187:drug effects / Q000235:genetics*; D003433:Crosses, Genetic; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D055785:Gene Knockdown Techniques; D017343:Genes, Plant; D056726:Genetic Association Studies; D005816:Genetic Complementation Test; D006575:Heterocyclic Compounds, 3-Ring / Q000378:metabolism* / Q000494:pharmacology; D007783:Lactones / Q000378:metabolism* / Q000494:pharmacology; D010641:Phenotype; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018520:Plant Shoots / Q000033:anatomy & histology* / Q000187:drug effects / Q000254:growth & development; D030821:Plants, Genetically Modified; D032107:Populus / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development
chemical_list: C000591191:GR24 strigolactone; D006575:Heterocyclic Compounds, 3-Ring; D007783:Lactones; D010940:Plant Proteins
keywords: 
  MAX4
  ; Populus × canescens; axillary meristem; branching; bud outgrowth; poplar; strigolactones; tree architecture