TY  - GEN
TI  - Investigating the impact of cell wall dynamics
on secondary growth regulation
CY  - Heidelberg
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/30034/
Y1  - 2021///
AV  - public
ID  - heidok30034
A1  - Schlamp, Theresa
N2  - The morphology of plants can be highly adaptive due to the plasticity governed by
postembryonic development. In plants, stem cell populations, called meristems are
maintained through the entire life and enable lifelong development. Longitudinal growth
is realized by the meristematic activity in the apices of the shoot and root, while lateral
growth is enabled by the activity of the vascular cambium that is able to produce
specialized tissues in a bifacial manner. Initially, the fascicular cambium is active solely
in vascular bundles. At a later stage of development, the fascicular cambium extends
and cells in the region between vascular bundles ? the so-called interfascicular region
? start to divide, cumulating in the post-embryonic establishment of the vascular
cambium. Its formation is potentially based on de-differentiation of differentiated cells.
However, how exactly this process is initiated is still poorly understood.
Here, I used the process of vascular cambium formation, as a unique model to study
cell fate change. To control the formation of vascular cambium, I used a genetic tool
that allowed me to induce auxin biosynthesis in a cell type-specific manner. Strikingly,
induction of auxin biosynthesis in fully differentiated starch sheath cells provoked a cell
fate change and initiated the formation of interfascicular cambium. Based on detailed
analysis of interfascicular cambium formation, nuclear auxin signaling is shown to be
critical for this process. Furthermore, I investigated the role of cell wall during vascular
cambium formation, as plant cells are immobilized by cell walls ? a rigid type of
extracellular matrix. The thereby fixed position of the cell can contain important
information for cell fate determination. Interestingly, extensive cell wall remodeling
takes place during cambium formation, as revealed by immunohistochemical
quantification of extensin abundance and pectin modifications. Genome-wide
transcriptional profiling upon auxin-induced interfascicular cambium formation further
supports this result, as genes related to cell wall remodeling were disproportionately
represented among differentially expressed genes. Finally, I demonstrated the
importance of cell wall remodeling during interfascicular cambium formation by blocking
auxin induced interfascicular cambium formation via inhibiting cell wall remodeling.
The reported change in cell wall composition during vascular cambium formation may
cause a change in the elasticity of the cell wall, which might in turn be a prerequisite for
lateral growth. To quantitatively measure the elasticity of cell walls, I established
Brillouin microscopy in our lab and investigated cell wall properties depending on their
orientation and localization. I was able to show that Brillouin microscopy is a suitable
method to further investigate cell wall mechanics and its impact in the field of plant
science.
ER  -