Understanding tissue specific compositions of bioenergy feedstocks through hyperspectral Raman imaging.

Hyperspectral Raman imaging was used to study the tissue/cell type specific distribution of lignin and cellulose polymers within the plant cell walls. Distinct differences in cell wall compositions were identified between two potential bioenergy feedstocks: corn stover and Eucalyptus globulus. Characteristic bands of 627, 1,175, 1,206, and 1,428 cm⁻¹ were only observed for corn stover and 1,381 cm⁻¹ was only present in E. globulus. One-dimensional and two-dimensional chemical maps of lignin and cellulose were generated for the stem of corn stover, ranging from the epidermis to the pith area and revealed that lignin and cellulose abundance varies significantly among different cell types in the following order: sclerenchyma cells and tracheids (∼5 times) > epidermal cells (∼3 times) > bundle sheath cells > parenchyma cells. The Raman mapping methods developed on corn stover were also validated on E. globulus and clearly highlighted their difference in lignin composition.