Dissecting plant cell walls into chemical components
We conduct research using chemical structure as a keyword to elucidate the mechanisms of plant cell wall formation, particularly in woody plants, and the characteristics of various plants as biomass resources. The cell walls of woody plants are composed of polysaccharides, such as cellulose and hemicellulose, as well as lignin, an aromatic polymer that plays a key role in lignification. Examining the structure of lignin makes it possible to estimate how it formed based on the history of its formation that remains in its chemical structure, as is the case with many other natural organic compounds. For example, the history of polymerization from monomers is retained in the stereochemical structure. Upon investigation, it was confirmed that lignin is optically inactive and polymerizes without being affected by enzymes or other factors that could affect its structure. This contrasts with the structural characteristics of some natural macromolecules, such as cellulose, proteins, and nucleic acids, whose stereochemistry is strictly controlled during biosynthesis. In addition, important information characterizing the properties of biomass resources, such as the partial structures that determine the shape and reactivity of polymers, is contained in the chemical structure of cell wall components. We are working on deriving such information using chemical methods.
Educational content
Cell Wall Components and their Role in Plants
Land plants are composed of cells with cell walls. These cell walls have a water-conducting function that transports water upward and enables plants to support their own weight against gravity and grow to an enormous size. These plants, such as trees, are well known to be deeply involved in the carbon cycle on Earth, including carbon dioxide fixation, humus decomposition, soil organic carbon, coalification, and renewable energy utilization. When we start talking on such a grand scale, the differences in cell wall components that we are studying in our research may seem insignificant. However, the morphology of plant bodies and the shape of cell walls vary greatly among the species, part, and tissue, and differences are also seen in the polymer components that make up the cell walls, as if in conjunction with these differences. The differences in these components are thought to affect the physical properties of cell walls, the humification process after the plant has completed its life cycle, and the utilization of plant resources. I would like students to immerse themselves in one specialized field, such as cell wall chemistry, even if only for a short period of time. Then to take a look at the carbon cycle and the use of plant resources from the perspective of a researcher or expert, and think together about how to get involved.
Prospects for joint research and industry-academia collaboration
Elucidating the properties of plant biomass raw materials
There are still many unknown aspects regarding plant components, especially polymer components, and I believe that it is important to understand properties of biomass raw materials from a chemical structural aspect. Once structural characteristics become clear, chemical reactivity can be predicted, providing useful information to design how it can be chemical and biologically transformed. As structural studies focusing on components essential for understanding the reactivity of cell walls (i.e., biomass resources), we have been conducting research on the stereochemical structure of lignin, biphenyl, diaryl ether, and spirodienone structures. The purpose of structural research is to clarify the properties of various biomass raw materials and use them in utilization development research. We have focused on wood so far, but we will begin work on various biomass resources such as bark, agricultural residues, resource plants, and industrial lignin. By organizing and classifying them based on their chemical structural characteristics, we aim to make their reactivity predictable and extract useful information for designing applications such as chemical conversion and bioconversion.
