The role of tryptophan as a biosynthetic precursor of indole-diterpenoid fungal metabolites: Continuing a debate

Whereas the first 14C-labelling studies indicated that the indole moiety of fungal indole-diterpenoids came from tryptophan, recent 13C-labelling has persuaded acceptance that indole-3-glycerol phosphate is the source instead. Reasoning, questioning suitability of the latter's protocol, is presented and experimental strategies for clarifying the present situation are proposed.