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Auxin controls gravitropic setpoint angle in higher plant lateral branches
Suruchi Roychoudhry1, Marta Del Bianco, Martin Kieffer
1Centre for Plant Sciences, University of Leeds, Leeds, LS2 9JT, UK.
Current Biology : CB
|July 30, 2013
Summary
Plant branches maintain specific angles to gravity using an auxin-driven mechanism. This system balances gravitropism with an antigravitropic offset, controlling the gravitropic setpoint angle (GSA) for angled growth.
Area of Science:
- Plant Biology
- Developmental Biology
- Gravitational Biology
Background:
- Higher plants exhibit lateral branches with specific angles relative to gravity, termed the gravitropic setpoint angle (GSA).
- GSA is crucial for plant architecture, but the mechanisms governing gravity-dependent angled growth remain largely unknown.
Purpose of the Study:
- To elucidate how stable, angled growth of plant branches is maintained.
- To determine the mechanisms by which the gravitropic setpoint angle (GSA) is established.
- To investigate the role of auxin in regulating GSA.
Main Methods:
- Investigated the interplay between gravitropism and an auxin-dependent antigravitropic offset mechanism.
- Analyzed the dependence of GSA on the magnitude of the antigravitropic offset.
- Examined auxin signaling pathways (TIR1/AFB-Aux/IAA-ARF) in gravity-sensing cells.
Main Results:
- Identified an auxin-dependent antigravitropic offset mechanism distinguishing nonvertical branches from the primary axis.
- Demonstrated that the GSA of lateral roots and shoots is determined by the strength of this antigravitropic offset.
- Showed that auxin dynamically regulates GSA by modulating the antigravitropic offset via specific signaling pathways.
Conclusions:
- Auxin plays a critical role in specifying the gravitropic setpoint angle (GSA) throughout plant development.
- The GSA is established through a balance between gravitropic response and an auxin-mediated antigravitropic offset.
- This provides a framework for understanding GSA determination in plants and highlights auxin's self-organizing capacity.
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