Auxin–cytokinin interactions in the control of shoot branching

We describe the molecular mechanisms of the interactions between auxin and cytokinin in the control of shoot branching

Sae Shimizu-Sato; Mina Tanaka; Hitoshi Mori

2008

Scholarcy highlights

  • Apical dominance is a phenomenon in which a main shoot in an intact plant grows predominantly while suppressing
  • Shoot branching has an important role in generating a large variety of diverse plant forms, because the degree of apical dominance varies depending on the plant species
  • We describe the molecular mechanisms underlying the interactions between auxin and CK in the control of shoot branching
  • Application of 1-naphthylacetic acid to the stump prevents the increase in CK in the bean xylem exudates. These observations led to the suggestion that CK derived from roots promotes axillary bud outgrowth after decapitation, and auxin derived from a shoot apex regulates CK transport in plants
  • CK levels in the stem and axillary buds increase 3 h after decapitation despite the fact that PsIPT2 is not expressed in growing axillary buds; CK is biosynthesized in the stem and transported into axillary buds to promote their outgrowth after decapitation
  • De novo synthesized indole-3-acetic acid derived from a new shoot apex flows to the stem, where it represses IPT expression and induces cytokinin oxidase to reduce the steady-state CK level in the stem

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