The influence of tryptophan and tryptamine feeding and light on alkaloid biosynthesis in cinchona seedlings.

It has previously been shown that, at the onset of germination of CINCHONA seeds, transient increases in both the tryptophan level and tryptophan decarboxylase (TDC) activity occur. Subsequently, in the seedlings the levels of the TDC product tryptamine and its derived alkaloids increase. We investigated whether this process can be influenced by external tryptophan or tryptamine feeding. Besides, the possible role of light in alkaloid biosynthesis was studied by monitoring this process in etiolated seedlings. Tryptophan feeding slightly raised the TDC activity in the seedlings, but alkaloid production remained unaltered. During tryptamine feeding, the transient increases in tryptophan level and TDC activity were still observed, and also here, alkaloid production remained unaltered. Finally, in etiolated seedlings the alkaloid biosynthetic pathway proceeded normally. Thus, in germinating CINCHONA seedlings alkaloid production is not susceptible to tryptophan or tryptamine feeding and independent of light.