Prh. Moreno et al., EFFECTS OF ELICITATION ON DIFFERENT METABOLIC PATHWAYS IN CATHARANTHUS-ROSEUS (L) DON,G. CELL-SUSPENSION CULTURES, Enzyme and microbial technology, 18(2), 1996, pp. 99-107
Cell suspension cultures of Catharanthus roseus were elicited with an
autoclaved cell-free filtrate of Pythium aphanidermatum. The regulatio
n of alkaloid, terpenoid, and phenolic biosynthetic pathways was studi
ed by product formation and assay of the enzyme activity of anthranila
te synthase (AS), tryptophan decarboxylase (TDC), strictosidine syntha
se (SSS), strictosidine-beta-glucosidase (SG), isopentenyl diphosphate
isomerase (IPP isomerase), geraniol-10-hydroxylase (G10H), chorismate
mutase (CM), and phenylalanine ammonia lyase (PAL). After elicitation
, AS and TDC activities were induced which resulted in an increase in
the amount of tryptamine in the cells. For SSS and SG, no significant
induction was observed. Ajmalicine accumulation was not increased comp
ared with that in controls. An increased amount of phenolic compounds
was found in the culture medium, although CM activity was not induced
and PAL activity was inhibited after elicitor treatment. The activitie
s of the enzymes IPP-isomerase and G10H were inhibited after elicitati
on. Also, the incorporation of [C-14]IPP in terpenoid products such as
squalene was inhibited. These findings indicate a limitation in the t
erpenoid pathway which could promote a shortage of secoiridoid precurs
ors for terpenoid indole alkaloid biosynthesis.