Phytochrome regulates cellular response plasticity and the basic molecular machinery of leaf development
Andrés Romanowski1,2, James J Furniss1, Ejaz Hussain1
1Halliday Lab, Institute of Molecular Plant Sciences (IMPS), King's Buildings, University of Edinburgh, Edinburgh, UK.
Plant Physiology
|March 11, 2021
Summary
Plants adapt to shade by altering leaf growth. The shade-avoidance syndrome (SAS) restricts leaf size by limiting cell division early in development or cell expansion later, controlled by light-sensing phytochromes.
Area of Science:
- Plant biology
- Developmental biology
- Photoreceptor signaling
Background:
- Plants exhibit phenotypic plasticity to optimize growth based on environmental cues.
- Light, particularly far-red light detected by phytochromes, signals vegetation density and triggers the shade-avoidance syndrome (SAS).
- SAS results in characteristic plant morphology, including elongated growth and reduced leaf blade size.
Purpose of the Study:
- To investigate the cellular mechanisms by which SAS restricts leaf blade size in Arabidopsis thaliana.
- To determine how the timing of far-red light exposure influences SAS-mediated leaf development.
- To identify the molecular pathways regulated by phytochromes during SAS.
Main Methods:
- Arabidopsis thaliana (thale cress) were subjected to end-of-day far-red (EoD FR) light treatments at different stages of leaf 3 development.
- Leaf growth was analyzed to assess the impact of SAS induction timing on cell division and expansion.
- mRNA sequencing (mRNAseq) time course data and bioinformatics analyses were used to identify regulated pathways.
Main Results:
- SAS restricts leaf blade size through two distinct temporal cellular strategies: limiting cell division upon early induction and limiting cell expansion upon later induction.
- Phytochromes maintain control over leaf size throughout both proliferative and expansion phases of leaf growth.
- Bioinformatics analysis of mRNAseq data revealed that phytochromes regulate key developmental pathways controlling cell division, expansion, cell fate, DNA replication, repair, and ribosome biogenesis.
Conclusions:
- Phytochromes employ a flexible, temporally regulated strategy to control leaf size in response to shade cues.
- The shade-avoidance syndrome involves the coordinated regulation of cell cycle progression, DNA maintenance, and protein synthesis machinery.
- Understanding these pathways provides insight into plant adaptation and development.
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