P-20　S/G比が段階的に異なるポプラを用いたリグニン基本骨格が発光特性に及ぼす影響

抄録

Lignin, a major cell wall component of lignocellulosics, is expected as a promising feedstock for the value-added materials due to its photoluminescence (PL) properties. In hardwood, sinapyl and coniferyl alcohols polymerize through radical coupling reactions to form syringyl (S) and guaiacyl (G) units, respectively. The ratio of S to G units (S/G ratio) is considered a key parameter for characterizing the chemical and physical structure. However, the effect of variations in S/G ratios on lignin PL properties remains unclear. In this study, the poplar with different S/G ratios were prepared by the overexpression of ferulate 5-hydroxylase (F5H) gene driven by cinnamate 4-hydroxylase promoter, and the cellulolytic enzyme lignin (CEL) was isolated from the transgenic lines to study the influence of S/G ratio on PL properties in solution. From the monomer yields of thioacidolysis, lignin of the produced transgenic poplars consisted of higher S/G ratio with a range of %S from 68.9% to 92.5% than wild type in 60.3%. When the PL properties of the isolated CELs from five transgenic lines were analyzed in N,N-dimethylformamide and chloroform solution, CELs from all lines clearly showed the PL. Notably, a significant negative correlation was observed between %S in transgenic lines and the PL intensity. It was apparent that the difference in lignin aromatic moiety influenced on the PL properties in solution.