Lignin is the most abundant natural aromatic polymer, and its quantitative and qualitative modification by genetic engineering is attracting attention towards its efficient conversion into value-added materials. In this study, the feruloyl-CoA 6'-hydroxylase gene (F6'H1) from Arabidopsis thaliana was overproduced in hybrid aspen to modify the lignin luminescence properties by the incorporation of scopoletin into lignin molecule. Cellulolytic enzyme lignin (CEL) was isolated from the transgenic aspens with various F6'H1-overproduced levels and evaluated for luminescence properties. Analysis of photoluminescence (PL) spectra of CEL in DMSO solutions showed high PL intensity with longer wavelengths in the F6'H1-overproduced aspen. The structure and distribution of the major chromophore, scopoletin, was discussed based on the spectral analysis in low-polarity solvents and structural analysis using gel permeation chromatography with a fluorescence detector. Furthermore, a reversible photodimerization reaction, characteristic of coumarins, was observed in F6'H1-overproduced aspen. These results suggest the great potential of genetic engineering strategy of the incorporation of scopoletin into lignin to produce the value-added materials.
