Our lab seeks to understand the molecular, cell biological, and developmental details of plant cell wall dynamics, more complete knowledge of which will allow for the efficient use of plant resources by human societies to produce food, renewable materials, and bioenergy. We use the model plants Arabidopsis thaliana and Physcomitrella patens as experimental systems. Our research focuses on three processes:

1) de novo cell wall formation
Each plant cell builds a new double-sided cell wall during every cell division by synthesizing a structure called the cell plate, which eventually fuses with existing cell walls to separate the new daughter cells. These new cell walls initially differ in their structure and composition from older cell walls, but mature to become similar to existing cell walls. However, many of the details of this maturation process are unknown. Because almost every cell wall in an adult plant begins as a cell plate, characterization of the molecular events and dynamics of this maturation process and the genes responsible for it is critical to understanding the development of plant structure at the cellular, tissue, and organismal levels.

A cartoon schematic of cell division and new wall formation in plant cells. The cell plate, which will become the new cell wall, forms via vesicle fusion and membrane remodeling at the midline of the phragmoplast, a microtubule-based structure that appears near the end of mitosis.
2) cell wall modification
Primary plant cell walls are amazing biological structures that are capable of growing and deforming along with the protoplasts they encase while withstanding the immense forces generated by turgor pressure. Using in vivo imaging approaches, our lab measures how cell walls are structurally and compositionally modified during cell growth, focusing on two classes of biopolymers: cellulose, a partially crystalline polymer of glucose that serves as the major load-bearing component of the cell wall, and pectins, which are components of the hydrated matrix within which cellulose is embedded. We have also identified and are characterizing a set of mutants with an enhanced cell growth phenotype in an effort to identify new genes that play roles in cell wall modification. These lines of research will be useful for the identification of plants with cell wall properties that are suitable for efficient bioenergy production.

A model of the rearrangements of some cell wall components during cell expansion. In elongating cells, cellulose (blue) is synthesized in a transverse orientation, but reorients toward a longitudinal orientation as the cell elongates. Pectin (green) is initially delivered to the cell wall in discrete locations, but spreads and associates with cellulose as the cell elongates.
3) cell wall recycling
Genetic and biochemical evidence indicates that plants degrade certain components of their cell walls in a controlled fashion during the processes of cellular growth and differentation. The extent to which these degradative processes contribute to and interface with cell wall biosynthesis, cell signaling, and intracellular metabolism is not fully understood. Analyzing cell wall recycling using cell biological and molecular approaches might enable the engineering of plants with customized, more easily degradable cell walls that are nonetheless able to withstand environmental and biotic stresses.



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