On the behavior of monolignol glucosides in lignin biosynthesis .3. Synthesis of variously labeled coniferin and incorporation of the label into syringin in the shoot of Magnolia kobus

To examine the possible in vivo conversion of coniferin to syringin in the biosynthetic pathway oi lignin, variously radio-labeled coniferin was fed to a shoot of Magnolia kobus. When coniferin-[side chain gamma-H-3, Glc-U-C-14] was administered, only H-3-activity was detected in syringin isolated from the shoot. The lack of C-14-activity In isolated syringin suggests that the conversion from guaiacyl to syringyl proceeded at the stage of monolignols, and the glucose moiety is temporally removed during the process of methoxylation. These results suggest the possible role of monolignols in the control of monomer composition of lignin.