The Academy Lecture

Katia RUEL

UNDERSTANDING WOOD AT THE NANOSCALE - ZOOMING THROUGH WOOD CELL WALL ULTRASTRUCTURAL ORGANIZATION

The Lecturer

I graduated from the Faculty of Orsay (University Paris-Sud) with a Master in Biological Sciences completed with the certificate for teaching ability (CAPES). After a one year period teaching biology, I moved to Grenoble and started a research formation in Plant Sciences that lead me to my PhD thesis, then to my Doctorate in Sciences and finally to my Research Habilitation in Biological Sciences.
I spent my whole career at the Scientific National Research Council (CNRS, France) first as Researcher, then as Director of Research in the Centre of Research on Plant Macromolecules (CERMAV, Grenoble). In relation with my formation and past and present activities in research, my primary interests
were in the following areas:
- Plant and Wood cell wall biology and biochemistry, evolution and diversity
- Polysaccharides and lignin distribution at the ultrastructural and nano-levels
- Macromolecular plant cell wall assembly.
- Relationship between wood microstructure and mechanical properties
- Wood degradation by fungi
- Fibre behaviour and alterations during processing in the pulp and paper industry
- Impact of enzymatic treatments on wood materials
- Biogenesis and formation of plant cell walls
- Characterization of modifications induced in genetically engineered plant and trees.
A great challenge in the transmission electron microscopy examination was to identify and characterize the chemical nature of the cell wall constituents in order to map their distribution in situ. In this respect, one of my first concerns has always been to develop novel methodologies and technologies for in-planta identification and visualization of wood macromolecules (polysaccharide staining, reducing-end silver labelling, enzyme-gold complexes, immunolabelling, carbohydrate binding domains, etc....) coupled to conventional microanalysis. Thus, combining analytical techniques and non-invasive approaches for the visualization of the cell wall components I studied the sequence of steps leading to the biogenesis of the cell walls during plant growth. With similar approaches I studied lignification and the distribution of the various forms of lignins in different types of model plants (Arabidopsis, Tobacco, Maize, Poplar ...) and in trees (Hardwoods, Softwoods) and in red algae (Calliarthron). These studies all pointed out the importance of the non-condensed forms of lignins versus the condensed forms in the cohesion of the lignocellulosic cell walls.
This was also evidenced in the process of degradation of wood by white-rot fungi as well as in the chemical degradation of woods in the pulping processes. The localization of hemicelluloses and lignins at the scale of cellulose microfibrils allowed proposing a model of elaboration of plant and wood secondary walls. Keeping these concepts in mind served as a basis for the understanding of the wood fibres deconstruction occurring during wood pulping or during biomass conversion.
Developing new tools and methodologies and transferring the knowledge and concepts acquired through fundamental research into applied investigation, constitute my general attitude and largely guide my research interests.

The lecture was presented during the 2012 IAWS Plenary Meeting in Zvolen/Slovakia

Understanding Wood at the Nanoscale – Zooming through Wood Cell Wall Ultrastructural Organization

In situ localization of matrix components