Dynamics of radial axis formation in Arabidopsis thaliana zygote
Description
Plants develop along apical-basal and radial axes. In Arabidopsis thaliana, the radial axis becomes evident when the cells of the 8-cell proembryo divide periclinally, forming inner and outer cell layers. Although changes in cell polarity or morphology likely precede this oriented cell division, the initial events and the factors regulating radial axis formation remain elusive. Here, we report that three transcription factors belonging to the class IV homeodomain-leucine zipper (HD-ZIP IV) family redundantly regulate radial pattern formation:HOMEODOMAIN GLABROUS11 (HDG11), HDG12, and PROTODERMAL FACTOR2 (PDF2). The hdg11 hdg12 pdf2 triple mutant failed to undergo periclinal division at the 8-cell stage and cell differentiation along the radial axis. Live-cell imaging revealed that the mutant defect is already evident in the behavior of the embryo’s initial cell (apical cell), which is generated by zygote division. In the wild type, the apical cell grows longitudinally and then radially, and its nucleus remains at the bottom of the cell, where the vertical cell plate emerges. By contrast, the mutant apical cell elongates longitudinally, and its nucleus releases from its basal position, resulting in a transverse division. Computer simulations based on the live-cell imaging data confirmed the importance of the geometric rule (the minimal plane principle and nucleus-passing principle) in determining the cell division plane. We propose that HDG11, HDG12, and PDF2 promote apical cell polarization, i.e., radial cell growth and basal nuclear retention, and set proper radial axis formation during embryogenesis.
Release date
2026-01-21
Updated date
-
License
CC BY 4.0
Kind
Image data
based on Experiment
Number of Datasets
6
( Image datasets: 6,
Quantitative data datasets: 0 )
(Abstract) Plants develop along apical-basal and radial axes. In Arabidopsis thaliana, the radial axis becomes evident when the cells of the 8-cell proembryo divide periclinally, forming inner and outer cell layers. Although changes in cell polarity or morphology likely precede this oriented cell division, the initial events and the factors regulating radial axis formation remain elusive. Here, we report that three transcription factors belonging to the class IV homeodomain-leucine zipper (HD-ZIP IV) family redundantly regulate radial pattern formation: HOMEODOMAIN GLABROUS11 (HDG11), HDG12, and PROTODERMAL FACTOR2 (PDF2). The hdg11 hdg12 pdf2 triple mutant failed to undergo periclinal division at the 8-cell stage and cell differentiation along the radial axis. Live-cell imaging revealed that the mutant defect is already evident in the behavior of the embryo's initial cell (apical cell), which is generated by zygote division. In the wild type, the apical cell grows longitudinally and then radially, and its nucleus remains at the bottom of the cell, where the vertical cell plate emerges. By contrast, the mutant apical cell elongates longitudinally, and its nucleus releases from its basal position, resulting in a transverse division. Computer simulations based on the live-cell imaging data confirmed the importance of the geometric rule (the minimal plane principle and nucleus-passing principle) in determining the cell division plane. We propose that HDG11, HDG12, and PDF2 promote apical cell polarization, i.e., radial cell growth and basal nuclear retention, and set proper radial axis formation during embryogenesis.
Contact
Minako Ueda
, Tohoku University
, Graduate School of Life Sciences
, Laboratory of Plant Cell Dynamics