Research

Cell fate control during plant development
Multicellularity allows organisms such as plants to form complex structures but these need to be carefully patterned and controlled. Spatial control of cell fate and patterning have been studied in some detail, as have time-controlled phase changes that affect an entire organ or individual. However, we have largely remained naïve to timing control along a cellular fate trajectory. What determines the relative timing of fate acquisition, progression, and differentiation along a cellular trajectory, and when and how is development slowed down or sped up? In our group, we investigate the mechanisms the plant uses to control the timing of cell fate transitions.

Delayed stomatal fate initiation
Stomatal fate acquisition during embryogenesis is delayed: SPCH is present as soon as the embryonic cotyledon epidermis exists but does not induce stomatal fate acquisition for several days (Smit et al. 2023 Dev Cell). This delay does not exist after germination: both in true leaves and in expanding cotyledons SPCH induces stomatal fate acquisition on the scale of hours rather than days. These findings indicate that currently unknown factors prevent initial stomatal lineage progression in the embryo. One of the early goals of our group is to identify which factors limit stomatal fate acquisition and what methods they use for limiting SPCH action.

Blocked embryonic differentiation
While many cell types are specified during embryogenesis, none differentiate. This makes intuitive sense as embryos do not require differentiated cells. However, I have found that the master regulators that normally drive stomatal differentiation are unable to act during embryogenesis (Smit et al. 2023 Dev Cell). How does the plant control the timing of differentiation and prevent it from happening in the embryo? We study what mechanisms and actors prevent master regulators from triggering cell differentiation during embryogenesis. We are using protophloem and stomatal development as our main models but also explore differentiation of other cell types.