Constructing a Comprehensive Picture of the Miscanthus Cell Wall to Advance Its Deconstruction

Panicoid grasses from the genus Miscanthus are among the most promising dedicated lignocellulosic energy crops. Despite their potential, cell wall recalcitrance to sugar release still hinders widespread use of its lignocellulosic biomass as bioenergy feedstocks. As a result, the advancement of our knowledge concerning the causes of recalcitrance is a pressing matter. To investigate the chemical, structural and biological features that underpin cell wall recalcitrance of Miscanthus biomass, we embarked on an in-depth cell-wall analysis following a multidimensional approach that considered different developmental stages, tissue types, and various genotypes. Results showed an inverse correlation between lignin content and ethanol production in stem tissues but not in leaves; while leaf tissue may contribute significantly to harvested biomass. FTIR spectroscopy showed that cell wall compositional differences between tissues are mostly associated to structural carbohydrates. We followed a glycome profiling approach to further elucidate these differences. Immunolocalization studies provided detailed information about in situ distributions of selected carbohydrate epitopes in mature stem and leaf tissues. Correlation of glycome profiling with immunolocalization, lignin content and biomass digestibility support the relevance of our approach for the construction of a detailed portrait of the cell wall in the context of lignocellulosic feedstocks. Ultimately, this expanded view will help steer breeding and engineering strategies for the development of superior energy crops and to a more advanced biorefining.