The leaf epidermis is a well-suited tissue to study cell fate acquisition in plants. In the stomatal lineage, stem cell-like meristemoids give rise to pavement cells and stomatal guard cells, which together account for over 80% of leaf epidermal cells.
Plant cells polarize and divide asymmetrically in order to achieve two daughter cells with different fates. Two proteins have been identified so far that account for cell polarization in the stomatal lineage. Immediately before cell division, these polarized proteins accumulate in membrane subdomains that are inherited by only one of the two daughter cells. Mutations in the corresponding genes lead to loss of asymmetry with regards to both size and fate of the daughter cells.
Mechanisms for cell polarization in the stomatal lineage that integrate the plethora of external signals, including hormones, cell-cell communication and mechanical cues are, as of yet, unknown. My research focuses on the interplay of mechanical and chemical signals, apparent in the leaf epidermis. Inducing artificial changes in the mechanical stress environment through cell ablations and tissue stretching, I could show that polarized proteins change their orientation throughout the tissue. This is coherent with changes of the global orientation of the microtubule cytoskeleton. How these processes are coordinated with each other and tie in with peptide signaling among epidermis cells is part of my ongoing investigation.
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