The role of ROP signaling in auxin-dependent oriented cell division

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Cells are fundamental building blocks of plant architecture. Cell shape maintenance and positioning of the wall during cell division are crucial for plant morphogenesis because of cell wall constraints. Orientation of division plane forms the basis for formative events, which determine the cell and tissue diversity during embryonic and post-embryonic development. Thus, understanding the mechanisms employed in this process is of central importance in plant cell and developmental biology. During Arabidopsis embryogenesis the orientation of the cell division plane in symmetric cell divisions is determined by a simple geometric default rule based on minimal surface area. By contrast, asymmetric cell divisions, which result in the formation of new tissue layers, deviate from this simple rule upon transcriptional auxin response. Further analysis on the molecular regulation of this phenomenon revealed MT-associated IQD proteins and signalling components of the small Rho GTPases, namely ROPs. In this project, I will use a combination of approaches involving genetics, molecular biology, cell biology and computational imaging analysis, to address how ROP activity regulates cell shape and division plane orientation during embryo development. I will investigate whether this involves regulation of plasma membrane polarity and cytoskeleton organization, and how these processes correlate with oriented cell division. Furthermore, I will explore how the interaction with ROP downstream signalling components like MT-binding IQDs regulate cell dynamics during early embryo patterning. The outcomes of this project will reveal novel signalling mechanisms at the plasma membrane-cytoskeleton interface that maintain cell shape and orient division planes during plant development.