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Updated: May 27, 2026

Confocal Live Imaging of Shoot Apical Meristems from Different Plant Species
Published on: March 29, 2019
Node-specific branching and heterochronic changes underlie population-level differences in Mimulus guttatus
Robert L Baker1, Pamela K Diggle
1Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, 80309, USA. Robert.Baker@colorado.edu
Mimulus guttatus shoot architecture reveals that branching occurs early at basal nodes, while flowering shifts distally in perennials. Developmental timing, not meristem limitation, drives differences in annual and perennial plants.
Area of Science:
- Plant developmental biology
- Evolutionary biology
- Plant morphology
Background:
- Shoot architecture is crucial for plant form, function, reproduction, and evolution.
- Mimulus guttatus is a model organism for evolutionary biology, yet its shoot development is understudied.
- Understanding shoot architecture provides insights into plant life history evolution.
Purpose of the Study:
- To investigate the developmental basis of shoot architecture in Mimulus guttatus.
- To compare branch and flower development in populations with contrasting life histories and flowering times.
- To explore potential trade-offs between branching and flowering in M. guttatus.
Main Methods:
- Examined branch and flower development in two M. guttatus populations with different life histories.
- Utilized controlled growth chamber conditions with second-generation seeds to minimize maternal and environmental effects.
- Analyzed branching patterns at basal and distal nodes and correlated with flowering time.
Main Results:
- Branching predominantly occurred at the first and second nodes of the main axis.
- Perennial M. guttatus exhibited earlier and more frequent branching than annuals.
- Flowering occurred at more distal nodes in perennials (fifth+) compared to annuals (third+).
Conclusions:
- No direct trade-off between flowering and branching was observed due to abundant quiescent axillary meristems.
- Basal node branch number is regulated by meristem initiation or outgrowth, not flowering vs. branching.
- Heterochronic processes (changes in developmental timing) influence flowering time and branch number differences between annual and perennial M. guttatus.
Related Concept Videos
Primary and Secondary Growth in Roots and Shoots
Morphogenesis
Meristems and Plant Growth
Multipotency and Niche of Bulge Stem Cell
Phylogeny
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