The present state and problems in lignin biosynthesis

The genes encoding enzymes in lignin biosynthesis and their expression mech anisms have been recently elucidated. The progress in molecular biology of lignin biosynthesis has prompted the genetic engineering to modifying ligni n structures suitable for pulping and wood biomass utilization. This paper outlines the present state and problems in biochemistry and molecular biolo gy of lignin biosynthesis. As an attempt to elucidate the chemical structur e of the abnormal lignin of cinnamyl alcohol dehydrogenase (CAD) down regul ated plants, DHPs and dimers from mixtures of coniferyl aldehyde and conife ryl alcohol were prepared as models, and the mode of linkages of coniferyl aldehyde in the DHPs has been characterized.