Strigolactone-Based Node-to-Bud Signaling May Restrain Shoot Branching in Hybrid Aspen

We identified previously undescribed Populus homologs of DWARF27, LATERAL BRANCHING OXIDOREDUCTASE and DWARF53-like and analyzed the relative expression of all SL pathway genes in root tips and shoot tissues

Niveditha Umesh Katyayini; P�ivi L H Rinne; Christiaan van der Schoot

2019

Scholarcy highlights

  • In deciduous trees, crown architecture arises through the coordinated action of terminal and axillary meristems
  • In Populus  canescens, knockdown of SL biosynthesis genes reduced BRC1 expression and induced branching, like knockdown of BRC1 and BRC2. These findings suggest that at least part of the SL biosynthesis and signaling genes as well as downstream targets are functional in Populus
  • As we found that SL pathway dynamics within the axillary buds-node complex reflected the transition from inactivity to activation, we hypothesized that an increase in SL content will prevent AXB activation
  • Mature AXBs can synthesize SL-like compounds downstream of CL, but probably not CL itself as MORE AXILLARY GROWTH3 and MORE AXILLARY GROWTH4 are not expressed in AXBs, while MORE AXILLARY GROWTH1 and LATERAL BRANCHING OXIDOREDUCTASE are
  • As most SL pathway genes are downregulated by decapitation within hours, and ahead of embryonic shoot elongation, SL might function in intact plants to inhibit AXB activation
  • The initial triggers of AXB activation differ between intact plants, decapitated plants and single-node systems, the ensuing growth processes rapidly converge
  • The developmental changes during axillary buds activation induced either by decapitation or isolation of the single-node systems and treated with or without GR24 were analyzed with one- or two-way analysis of variance and combined with Fisher’s LSD test

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