Unraveling Plant Cell Wall Assembly: From Cellulose Synthesis and Xylan Patterning to Lignification
Restricted (Penn State Only)
- Author:
- Pfaff, Sarah
- Graduate Program:
- Plant Biology (PHD)
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- February 15, 2024
- Committee Members:
- Ying Gu, Outside Unit & Field Member
Daniel Cosgrove, Chair & Dissertation Advisor
Gabriele Monshausen, Major Field Member
Teh-Hui Kao, Program Head/Chair
B Nixon, Major Field Member - Keywords:
- plant cell wall
cellulose
xylan
lignin
microscopy
cryoEM
X-ray scattering
NMR
CBM
cellulose synthase
xylem vessels
primary cell wall
secondary cell wall
cryoET
microtubules
actin
golgi
protoplasts
FIB milling
tomography - Abstract:
- Plant cell walls provide support and enable growth at the cellular level while also maintaining a plant’s stature. Cell walls are composed of various polysaccharides that may be extracted and converted into usable products. Sugar units and aromatic building blocks are synthesized and assembled by the coordination of numerous cellular pathways. The resultant polymers organize together to form unique cell walls in different cell types. To efficiently extract and deconstruct these energy-rich biomaterials, a better understanding of how they are initially produced and the complex ways in which they assemble is required. This work details a multifaceted effort to characterize the structure and formation of various types of cell walls. Beginning with the development of new methods to observe cell wall structure, we describe a novel fluorescent label that can be used to highlight recently-deposited crystalline cellulose fibrils and the optimization of a system to induce secondary cell wall (SCW) regeneration in isolated protoplasts. The latter technique enables observation of SCW development in individual cells, in a tissue-free environment, and was employed to characterize the key role the polysaccharide xylan plays in patterned SCW formation. Regenerating protoplasts were also used in an effort to produce the first in vivo reconstruction of an active cellulose synthase complex during SCW formation. Finally, a multidimensional study was conducted to track the deposition of SCWs during inflorescence stem maturation, with a particular focus on the process of lignification. In sum, the results produced by these research endeavors serve to improve our understanding of cell wall assembly and organization while also providing new tools to researchers for continued investigations of plant cell wall structure and formation.