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Multicellularity allows organisms such as plants to form complex structures but these need to be carefully controlled in both space and time. What determines the relative timing of cell fate acquisition, progression, and differentiation along a cellular trajectory, and when/how is development slowed down or sped up? In our group, we investigate the mechanisms the plant uses to control the timing of two main cell fate transitions in the embryo: stomatal fate acquisition and differentiation.
Stomatal fate acquisition during embryogenesis is delayed: The stomatal initiator SPCH is present as soon as the embryonic cotyledon epidermis exists but does not induce stomatal fate acquisition for several days. 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. We are studying how stomatal regulation is differently wired during embryogenesis.
In addition to fate acquisition, stomatal differentiation is also delayed during embryogenesis. No cell types differentiate in the Arabidopsis embryo, but I found that factors that normally drive stomatal differentiation cannot do so during embryogenesis. We have now identified several mutants where stomatal cells undergo either full or partial differentiation and are trying to understand the underlying mechanisms responsible.
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