Arrested Development – How do plants control fate transition timing?

• Applicant: Dr. Margot Smit
• Subject Area: Plant Cell and Developmental Biology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 534829971

Plants are complex organisms with precisely patterned tissues. Cells within each tissue need to perform specialized functions. Because of that, patterning and cell identity assignment are tightly controlled in the plant. Starting from a naïve stem cell-like identity, cells undergo a series of changes as they progress in their identity before differentiating and fulfilling their role, whether that be photosynthesis, transport (vascular cells), or gas exchange (stomata). How cell identities are assigned and what factors drive cell differentiation has been the subject of many studies in plant (and animal) research. For optimal control and coordination, cells need to progress to the right identity stage at the right time. So far, we know little about the mechanisms the plant uses to control the timing of identity progression. How does the plant control when the step can take place? My lab will study temporal regulation of identity progression. We will use developmental slowdowns that I have identified in the Arabidopsis embryo where stomatal and vascular cells are halted in their development. This slowdown is surprising because the factors we associate with the next step in identity progression are sometimes already there. And even when we tried to push development forwards by supplying more of the factors that we know to be able to drive progression, the cells in the embryo were still unable to change. This shows that the plant is preventing identity progression when it is unsuitable, but we do not yet know how. In this project we will find and study the mechanisms that the plant uses to control vascular and stomatal cell identity progression during embryogenesis. We will study (1) what mechanisms limit when cells can become stomatal cells and (2) how cell differentiation is halted in the embryo. This work will help us understand an unexplored dimension of plant biology and will set up future studies looking at timing in plant development. Once we understand better how the plant controls timing on a cellular level, we can learn more about coordination and patterning during development.

• DFG Programme: Independent Junior Research Groups