Integration of the SMXL/D53 strigolactone signalling repressors in the model of shoot branching regulation in <i>Pisum sativum</i>

  • Stephanie C. Kerr
    ARC Centre for Plant Success in Nature and Agriculture School of Biological Sciences The University of Queensland St Lucia Qld 4072 Australia
  • Suyash B. Patil
    National Key Facility for Crop Gene Resources and Genetic Improvement ICS, CAAS Beijing 100081 China
  • Alexandre de Saint Germain
    Institut Jean‐Pierre Bourgin INRAE AgroParisTech Université Paris‐Saclay 78000 Versailles France
  • Jean‐Paul Pillot
    Institut Jean‐Pierre Bourgin INRAE AgroParisTech Université Paris‐Saclay 78000 Versailles France
  • Julie Saffar
    Institut Jean‐Pierre Bourgin INRAE AgroParisTech Université Paris‐Saclay 78000 Versailles France
  • Yasmine Ligerot
    Institut Jean‐Pierre Bourgin INRAE AgroParisTech Université Paris‐Saclay 78000 Versailles France
  • Grégoire Aubert
    Agroécologie AgroSup Dijon INRAE Univ. Bourgogne Univ. Bourgogne Franche‐Comté F‐21000 Dijon France
  • Sylvie Citerne
    Institut Jean‐Pierre Bourgin INRAE AgroParisTech Université Paris‐Saclay 78000 Versailles France
  • Yannick Bellec
    Institut Jean‐Pierre Bourgin INRAE AgroParisTech Université Paris‐Saclay 78000 Versailles France
  • Elizabeth A. Dun
    ARC Centre for Plant Success in Nature and Agriculture School of Biological Sciences The University of Queensland St Lucia Qld 4072 Australia
  • Christine A. Beveridge
    ARC Centre for Plant Success in Nature and Agriculture School of Biological Sciences The University of Queensland St Lucia Qld 4072 Australia
  • Catherine Rameau
    Institut Jean‐Pierre Bourgin INRAE AgroParisTech Université Paris‐Saclay 78000 Versailles France

抄録

<jats:title>Summary</jats:title><jats:p>DWARF53 (D53) in rice (<jats:italic>Oryza sativa</jats:italic>) and its homologs in Arabidopsis (<jats:italic>Arabidopsis thaliana</jats:italic>), SUPPRESSOR OF MAX2‐LIKE 6 (SMXL6), SMXL7 and SMXL8, are well established negative regulators of strigolactone (SL) signalling in shoot branching regulation. Little is known of pea (<jats:italic>Pisum sativum</jats:italic>) homologs and whether D53 and related SMXLs are specific to SL signalling pathways. Here, we identify two allelic pea mutants, <jats:italic>dormant3</jats:italic> (<jats:italic>dor3</jats:italic>), and demonstrate through gene mapping and sequencing that DOR3 corresponds to a homolog of D53 and SMXL6/SMXL7, designated PsSMXL7. Phenotype analysis, gene expression, protein and hormone quantification assays were performed to determine the role of PsSMXL7 in regulation of bud outgrowth and the role of PsSMXL7 and D53 in integrating SL and cytokinin (CK) responses. Like D53 and related SMXLs, we show that PsSMXL7 can be degraded by SL and induces feedback upregulation of <jats:italic>PsSMXL7</jats:italic> transcript. Here we reveal a system conserved in pea and rice, whereby CK also upregulates <jats:italic>PsSMXL7</jats:italic>/<jats:italic>D53</jats:italic> transcripts, providing a clear mechanism for SL and CK cross‐talk in the regulation of branching. To further deepen our understanding of the branching network in pea, we provide evidence that SL acts via PsSMXL7 to modulate auxin content via <jats:italic>PsAFB5</jats:italic>, which itself regulates expression of SL biosynthesis genes. We therefore show that PsSMXL7 is key to a triple hormone network involving an auxin–SL feedback mechanism and SL–CK cross‐talk.</jats:p>

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