Abstract
Coumarins, which have antimicrobial and antioxidative activities, are often found in the plant kingdom. Enzymes related to coumarin biosynthesis in plants are unclear, although the coumarins are known to be biosynthesized via the phenylpropanoid pathway. The coumarins, scopoletin and its glucoside, scopolin, were detected in Arabidopsis thaliana root. We report here the methyltransferase related to biosynthesis of scopoletin and scopolin in A. thaliana.
We analyzed the coumarins in the T-DNA insertion mutant of caffeoyl CoA O-methyltransferase 1 (CCoAOMT1, At4g34050), which shows the highest expression level of the CCoAOMTs in A. thaliana. The levels of scopoletin and scopolin in the ccoaomt1 roots were ~15% of those in the wild type, suggesting that they were biosynthesized via CCoAOMT in A. thaliana. The levels of esculetin, esculin and cichoriin, which are the coumarins without methylation at 6-hydroxy group, were ~25-fold of those of wild type.
