Figure: (top) An overview of how periclinal cell divisions contribute to shaping the vascular cell lineage throughout plant development. Adapted from Smet and De Rybel (2016) Current Opinion in Plant Biology - PMID:26724501). (bottom) The level of TMO5/LHW heterodimer controls radial expansion of the Arabidopsis root by controlling the amount of periclinal and radial cell divisions.
The plant vascular system develops from a handful of provascular initial cells in the early embryo into a whole range of different cell types in the mature plant (see Figure above). In order to account for such proliferation and to generate this kind of diversity, vascular tissue development relies on a large number of highly oriented cell divisions. Different hormonal and genetic pathways, such as for example the TARGET OF MONOPTEROS5 / LONESOME HIGHWAY (TMO5/LHW) pathway, have been implicated in this process and several of these have been recently interconnected. Nevertheless, how such networks control the actual division plane orientation and how they interact with the generic cell cycle machinery to coordinate these divisions remains a major unanswered question that we are currently addressing in our lab.
Figure: The VASC DEV team in the summer of 2018