Elicitor-Stimulated Furanocoumarin Biosynthesis in Cultured Parsley Cells: S-Adenosyl-L-Methionine:BergaptoI and S-Adenosyl-L-Methionine: Xanthotoxol O-Methyltransferases

Furanocoumarins, Phytoalexins, O-Methyltransferases, Fungal Elicitor, Cell Suspension Cultures Cultured parsley cells (Petroselinum crispum) treated with an elicitor from the soybean patho­ gen, Phytophthora megasperma f. sp. glycinea, were used as source for the separation, extensive purification and characterization of S-adenosyl-L-methionine: xanthotoxol and S-adenosyl-Lmethionine: bergaptol O-methyltransferases. The products, xanthotoxin and bcrgapten, were among the most abundant coumarin derivatives accumulated in the culture fluid of elicitor-treated parsley cells. The latter enzyme also catalyzed the methylation of 5-hydroxyxanthotoxin to isopimpinellin, another major coumarin derivative in this system. The activities of both enzymes showed transient increases upon elicitor application prior to the accumulation of the products. No activity was detectable in untreated cells. Activity increases of the O-methyltransferases occurred a few hours later than those of phenylalanine ammonia-lyase and 4-coumarate:CoA ligase.