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Interactions between auxin and strigolactone in shoot branching control
Alice Hayward1, Petra Stirnberg, Christine Beveridge
1University of Queensland, School of Biological Sciences, Australian Research Council Centre of Excellence for Integrative Legume Research, Queensland 4072, Australia.
Plant Physiology
|July 31, 2009
Summary
Plant hormones auxin and strigolactone regulate each other in a feedback loop. This interaction controls plant branching by modulating MORE AXILLARY GROWTH3 (MAX3) and MAX4 gene expression.
Area of Science:
- Plant Biology
- Molecular Genetics
- Hormone Signaling
Background:
- Strigolactones are plant hormones crucial for inhibiting axillary bud outgrowth.
- MORE AXILLARY GROWTH3 (MAX3) and MAX4 are key genes in strigolactone biosynthesis.
- Axillary bud outgrowth is a critical trait for plant architecture and crop yield.
Purpose of the Study:
- To investigate the regulation of MAX3 and MAX4 gene expression by auxin.
- To explore the evolutionary conservation of auxin regulation on strigolactone biosynthesis genes.
- To elucidate the role of auxin-MAX3/MAX4 interaction in controlling plant branching.
Main Methods:
- Transcriptional analysis of MAX3 and MAX4 in Arabidopsis thaliana.
- Comparison of gene regulation patterns with orthologous genes in pea and rice.
- Analysis of gene expression in max mutants to understand feedback mechanisms.
Main Results:
- MAX3 and MAX4 transcript levels are positively regulated by auxin, conserved across plant species.
- Reduced auxin levels lead to decreased MAX3/MAX4 expression and increased axillary branching.
- MAX3 and MAX4 transcripts are upregulated in max mutants, indicating feedback regulation involving auxin signaling.
Conclusions:
- Auxin positively regulates the expression of strigolactone biosynthesis genes MAX3 and MAX4.
- A conserved feedback loop exists where auxin and strigolactone modulate each other's levels and distribution.
- This dynamic hormonal crosstalk is essential for the coordinated control of axillary branching in plants.
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