Conserved molecular compatibility for MIZ1 function in cytokinin signaling in land plants
- 1Institute of Science and Technology Austria (IST Austria)
Abstract
Plant roots adjust their growth direction toward water through hydrotropism, a process that in Arabidopsis thaliana requires the endoplasmic reticulum (ER)-associated protein MIZU-KUSSEI1 (MIZ1). Nonetheless, MIZ1 orthologues occur throughout land plants, including lineages lacking true roots, raising questions about the ancestral function of this protein family. Here, we investigated the evolutionary conservation and functional diversification of MIZ1-like proteins across land plants. MIZ1 orthologues from evolutionarily distant land plants failed to restore hydrotropism or cytokinin sensitivity in the Arabidopsis miz1 mutant, despite conserved protein structure and ER localization. In the liverwort Marchantia polymorpha, loss of MpMIZ1a led to altered cytokinin sensitivity and cytokinin-mediated development in both the sporophyte and gametophyte. These phenotypes and gene expression analyses imply a conserved role of MIZ1 in cytokinin-related processes. Despite this functional similarity, protein-protein docking and bimolecular fluorescence complementation revealed species-specific interactions between MIZ1 proteins and their cognate cytokinin histidine kinase receptors in Arabidopsis and Marchantia. Together, our findings indicate that MIZ1 proteins represent ancient land plant regulators of cytokinin-dependent development whose molecular compatibility and developmental outputs have diverged during evolution. We propose that the role of MIZ1 in root hydrotropism represents a derived recruitment of this ancestral module into root-specific environmental response pathways.
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BibTeX
@misc{smoljan2026conserved,
title = {{Conserved molecular compatibility for MIZ1 function in cytokinin signaling in land plants}},
author = {A. Smoljan and S. Das and D. Vladimirtsev and A. Teplova and M. Tkachenka and W. Yang and M. Lu and E. Benkova and J. Friml},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.12.758437},
url = {https://www.biorxiv.org/content/10.64898/2026.10.12.758437v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Conserved molecular compatibility for MIZ1 function in cytokinin signaling in land plants
AU - A. Smoljan
AU - S. Das
AU - D. Vladimirtsev
AU - A. Teplova
AU - M. Tkachenka
AU - W. Yang
AU - M. Lu
AU - E. Benkova
AU - J. Friml
PY - 2026
DA - 2026/10/12
PB - bioRxiv
DO - 10.64898/2026.10.12.758437
UR - https://www.biorxiv.org/content/10.64898/2026.10.12.758437v1
AB - Plant roots adjust their growth direction toward water through hydrotropism, a process that in Arabidopsis thaliana requires the endoplasmic reticulum (ER)-associated protein MIZU-KUSSEI1 (MIZ1). Nonetheless, MIZ1 orthologues occur throughout land plants, including lineages lacking true roots, raising questions about the ancestral function of this protein family. Here, we investigated the evolutionary conservation and functional diversification of MIZ1-like proteins across land plants. MIZ1 orthologues from evolutionarily distant land plants failed to restore hydrotropism or cytokinin sensitivity in the Arabidopsis miz1 mutant, despite conserved protein structure and ER localization. In the liverwort Marchantia polymorpha, loss of MpMIZ1a led to altered cytokinin sensitivity and cytokinin-mediated development in both the sporophyte and gametophyte. These phenotypes and gene expression analyses imply a conserved role of MIZ1 in cytokinin-related processes. Despite this functional similarity, protein-protein docking and bimolecular fluorescence complementation revealed species-specific interactions between MIZ1 proteins and their cognate cytokinin histidine kinase receptors in Arabidopsis and Marchantia. Together, our findings indicate that MIZ1 proteins represent ancient land plant regulators of cytokinin-dependent development whose molecular compatibility and developmental outputs have diverged during evolution. We propose that the role of MIZ1 in root hydrotropism represents a derived recruitment of this ancestral module into root-specific environmental response pathways.
ER -