SU seminar: Prof. Yuki Tobimatsu – Grass versus trees: from perspectives of lignin structure and biosynthesis

Title: Grass versus trees: from perspectives of lignin structure and biosynthesis

Speaker: Yuki Tobimatsu, Research Institute for Sustainable Humanosphere, Kyoto University (Japan) (https://scholar.google.com/citations?user=fYT6hRsAAAAJ) 

Abstract: 

Monocotyledonous grasses have evolved unique cell wall structures that differ significantly from those of typical wood species such as softwoods (gymnosperms) and hardwoods (eudicots). Notably, grasses produce lignins highly decorated by hydroxycinnamates (p-coumarates and ferulates) and flavonoid tricin units by incorporating grass-specific lignin monomers, i.e., γ-acylated monolignols, a flavonoid tricin, and feruloylated arabinoxylan. This contrasts with typical eudicot and gymnosperm species that utilize the canonical (non-acylated) monolignols as the sole lignin monomers for cell wall lignification. Currently, it remains largely unknown how such grass-specific lignin monomers are biosynthesized and function in grass cell walls. Moreover, how these lignin decorations affect the utility of grass biomass remains poorly understood. In this context, our group has been investigating the biosynthesis of the grass-specific lignin monomers and exploring bioengineering approaches (e.g., genome editing) to produce transgenic and mutant grass plants with altered lignin decoration units. In this presentation, I will briefly summarize our recent findings regarding the biosynthesis of grass-specific lignin monomers in rice, a model grass species and an economically important grass crop, and present some structure and property data of transgenic and mutant rice plants that produce cell walls lacking the grass-specific lignin decorations. We contemplate that deepening our understanding of the biosynthesis and properties of grass cell walls may contribute to a better understanding of the nature and evolution of woody cell walls.