Using serpentine fluorescence as an indicator of alkaloid production in cultured CATHARANTHUS ROSEUS cells, 6 cell lines producing alkaloid in excess of 300 mg/l were selected from more than 2 x 10 (5) individual colonies and their alkaloid production was monitored over a period of 8 years. Rapid loss of productivity invariably occurred during the first few months of cultivation, and spontaneous recovery of the initial production rates was never observed. Production of the indole alkaloid precursor, secologanin, followed the same pattern. Recovery of high alkaloid yielding strains was, however, possible at any time by repetition of the clonal selection procedure, but these strains were again instable. Clonal selection of high yielding plant cell strains apparently favours an inherent instability.

No abstract

Feeding experiments with glucose- (2-14C), phenylalanine- (3-14C), tyrosine- (3-14C) and p-coumaric acid- (3-14C) showed that the latter three substances are incorporated in good yields into p-hydroxybenzoic acid in leaves of Catalpa ovata. Kinetic experiments showed that p-hydroxybenzoic acid is formed from phenylalanine via p-coumaric acid and the subsequent β-oxidation of the side chain. p-Hydroxybenzoic acid can also be synthetised by hydroxylation of benzoic acid, but this does not seem to be the biosynthetic route in Catalpa.Phenylalanine- (3-14C) is also incorporated into benzoic acid, protocatechuic acid, and vanillic acid by different plants; the radioactivity of the β-C atom of the amino acid was found in each case to be located in the carboxyl group of the C6 — C1 acid. This suggests that in higher plants the benzoic acids are formed from the corresponding cinnamic acids via β-oxidation.