Effect of precursor feeding on alkaloid accumulation by a tryptophan decarboxylase over-expressing transgenic cell line T22 of Catharanthus roseus

• Published in: Journal of biotechnology 2002-06, Vol.96 (2), p.193-203
• Main Authors: Whitmer, Serap, van der Heijden, Robert, Verpoorte, Robert
• Format: Article
• Language: English
• Subjects: Alkaloids - metabolism; Aromatic-L-Amino-Acid Decarboxylases - biosynthesis; Biological and medical sciences; Biotechnology; Catharanthus - cytology; Catharanthus - enzymology; Catharanthus - genetics; Catharanthus - metabolism; Cell culture; Cells, Cultured; Establishment of new cell lines, improvement of cultural methods, mass culture; Eukaryotic cell cultures; Fundamental and applied biological sciences. Psychology; Genetic engineering; Methods. Procedures. Technologies; Molecular Structure; Plant cells and fungal cells; Plants, Genetically Modified - cytology; Plants, Genetically Modified - enzymology; Plants, Genetically Modified - genetics; Plants, Genetically Modified - metabolism; Plants, Medicinal - cytology; Plants, Medicinal - enzymology; Plants, Medicinal - genetics; Plants, Medicinal - metabolism; Secondary metabolism; Strictosidine synthase; Terpenoid indole alkaloids; Tryptophan decarboxylase
• ISSN: 0168-1656; 1873-4863
• DOI: 10.1016/S0168-1656(02)00027-5

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 μmol l −1 of TIAs whereas the control cultures accumulated less than 10 μmol l −1 TIAs.