A complex balance: PLETHORA - JANUS ratiometry explains the PLETHORA dosage regeneration paradox
- 1Utrecht University
Abstract
Molecular gradients are classically thought to encode positional information through concentration thresholds, but how transcription factor dosage is translated into regenerative competence remains unclear. In Arabidopsis roots, PLETHORA (PLT) transcription factors form a gradient that defines a regeneration competence zone and, following injury, rapidly re-establishes their transcriptional domain through an auto-activation. Yet, increasing PLT levels has a paradoxical effect: moderate increases expand the competence zone, whereas further increases impair regeneration. Here, combining mathematical modelling with experiments, we uncover the molecular basis of this non-monotonic response. Our model reveals that PLT activity depends not simply on its abundance, but on the balance between PLT protein complexes and unbound PLT. Following injury, PLT auto-activation rapidly restores the transcriptional domain, whereas increasing PLT dosage progressively shifts the equilibrium towards unbound PLT, reducing the availability of active PLT complexes. We identify and experimentally validate a strategy to extend regeneration competence by maintaining an appropriate ratio of PLT complexes to unbound PLT. Our findings reveal a ratiometric mechanism for decoding transcription factor dosage, in which excess regulator can attenuate rather than enhance activity. Such molecular balancing provides a mechanism by which a single transcription factor gradient can generate distinct, context-dependent outcomes during development and regeneration.
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BibTeX
@misc{gomez2026complex,
title = {{A complex balance: PLETHORA - JANUS ratiometry explains the PLETHORA dosage regeneration paradox}},
author = {M. L. Garcia Gomez and M. Mathew and S. Das and C. Roelofsen and V. Willemsen and K. Prasad and K. H. ten Tusscher},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.15.759210},
url = {https://www.biorxiv.org/content/10.64898/2026.10.15.759210v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - A complex balance: PLETHORA - JANUS ratiometry explains the PLETHORA dosage regeneration paradox
AU - M. L. Garcia Gomez
AU - M. Mathew
AU - S. Das
AU - C. Roelofsen
AU - V. Willemsen
AU - K. Prasad
AU - K. H. ten Tusscher
PY - 2026
DA - 2026/10/15
PB - bioRxiv
DO - 10.64898/2026.10.15.759210
UR - https://www.biorxiv.org/content/10.64898/2026.10.15.759210v1
AB - Molecular gradients are classically thought to encode positional information through concentration thresholds, but how transcription factor dosage is translated into regenerative competence remains unclear. In Arabidopsis roots, PLETHORA (PLT) transcription factors form a gradient that defines a regeneration competence zone and, following injury, rapidly re-establishes their transcriptional domain through an auto-activation. Yet, increasing PLT levels has a paradoxical effect: moderate increases expand the competence zone, whereas further increases impair regeneration. Here, combining mathematical modelling with experiments, we uncover the molecular basis of this non-monotonic response. Our model reveals that PLT activity depends not simply on its abundance, but on the balance between PLT protein complexes and unbound PLT. Following injury, PLT auto-activation rapidly restores the transcriptional domain, whereas increasing PLT dosage progressively shifts the equilibrium towards unbound PLT, reducing the availability of active PLT complexes. We identify and experimentally validate a strategy to extend regeneration competence by maintaining an appropriate ratio of PLT complexes to unbound PLT. Our findings reveal a ratiometric mechanism for decoding transcription factor dosage, in which excess regulator can attenuate rather than enhance activity. Such molecular balancing provides a mechanism by which a single transcription factor gradient can generate distinct, context-dependent outcomes during development and regeneration.
ER -