Plant cells are surrounded by rigid walls that prevent cell migration, and therefore formative cell divisions are critical to generate a functional body pattern from a single embryonic cell. Division plane orientation is an important determinant of formative cell divisions and pattern formation. A major unanswered question is how division plane orientation is genetically controlled, and in particular how this relates to cell geometry. Classical models in the 19th century predicted that cell geometry constrains division plane through a simple physical rule, which is approximated as the shortest wall passing through the center of the cell. Our group has recently shown that this geometric default rule can explain most of the divisions in the early Arabidopsis embryo in 3D (Yoshida et al., 2014). However, all asymmetric divisions disobeyed this rule. Interestingly, in auxin-insensitive Arabidopsis embryos all divisions can be explained by the geometric default rule, suggesting that transcriptional response to the auxin hormone is required to suppress default divisions. This knowledge allows us to mechanistically dissect the regulation of oriented cell division by geometric and genetic cues.
In my project, I am using a combined genetic, cell biological, molecular and computational approach to address how auxin dependent gene regulation suppresses default divisions, and what cellular reorganization mediates this activity. Furthermore, the conservation of this hormone-dependent mechanism will be explored in a variety of cell geometries, plant organs and plant species. The outcomes of this project are expected to connect developmental regulators to the cell division machinery and thus to fill a major gap in our knowledge on how supracellular development is implemented into individual cell behavior.
Yoshida, S.*, Barbier de Reuille, P.*, Lane, B., Bassel, G.W., Prusinkiewicz, P., Smith, R.S., Weijers, D. (2014). Genetic control of plant development by overriding a geometric division rule. Dev Cell Apr 14;29(1):75-87. doi: 10.1016/j.devcel.2014.02.002