title: Effect of precursor feeding on alkaloid accumulation by a tryptophan decarboxylase over-expressing transgenic cell line T22 of Catharanthus roseus.
abstract: To obtain more insight into the regulation of terpenoid indole alkaloid (TIA) biosynthesis in Catharanthus roseus (L.) G. Don cell cultures and particularly to identify possible rate limiting steps, a transgenic cell line over-expressing tryptophan decarboxylase (Tdc), and thus having a high level of tryptamine, was fed with various amounts of precursors (tryptophan, tryptamine, loganin and secologanin) in different time schedules and analyzed for TIA production. When these precursors were added to this culture it was found that the optimal time for supplying the precursors was at inoculation of the cells into the production medium. Alkaloid accumulation by line T22 was enhanced by addition of loganin or secologanin; however, the secologanin feeding was less effective. Tryptamine or tryptophan alone had no effect on TIA accumulation. The over-expression of Tdc causes this cell line to produce quite large quantities of alkaloids after feeding loganin or secologanin. However, in combination with tryptophan or tryptamine, feeding of these precursors resulted in an even further increase of alkaloid accumulation and under optimal conditions line T22 accumulated around 1200 micromol l(-1) of TIAs whereas the control cultures accumulated less than 10 micromol l(-1) TIAs.
authors.affiliation: Gorlaeus Laboratories, Division of Pharmacognosy, LACDR, Leiden/Amsterdam Center for Drug Research, Leiden University, Einsteinweg 55, PO Box 9502, 2300 RA Leiden, The Netherlands.
authors.forename: Serap
authors.initials: S
authors.lastname: Whitmer
authors.forename: Robert
authors.initials: R
authors.lastname: van der Heijden
authors.forename: Robert
authors.initials: R
authors.lastname: Verpoorte
mesh_terms: D000470:Alkaloids / Q000378:metabolism*; D001142:Aromatic-L-Amino-Acid Decarboxylases / Q000096:biosynthesis*; D030008:Catharanthus / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D015394:Molecular Structure; D030821:Plants, Genetically Modified / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D010946:Plants, Medicinal / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000378:metabolism
chemical_list: D000470:Alkaloids; D001142:Aromatic-L-Amino-Acid Decarboxylases