Elicitor-mediated induction of phenylalanine ammonia lyase and tryptophan decarboxylase: accumulation of phenols and indole alkaloids in cell suspension cultures of Catharanthus roseus.
Cell suspension cultures (cell line No. 615) of C. roseus cv. Little Delicata responded to treatment with fungal extracts from Pythium aphanidermatum by accumulating monoterpenoid indole alkaloids and phenolic compounds. The excretion of phenols into the culture medium resulted from the induction of the branch-point enzyme phenylalanine ammonia-lyase. The accumulation of alkaloids, however, occurred several hours earlier than the elicitor-mediated induction of tryptophan decarboxylase through which shikimate pathway intermediates are channelled into tryptamine and related indole alkaloids. The results indicate that both pathways for phenol and indole alkaloid biosynthesis responded to elicitor treatment and that no obvious causal relationship between pathways could be deduced.