Influence of Precursor Availability on Alkaloid Accumulation by Transgenic Cell Line of Catharanthus roseus1

Abstract

We have used a transgenic cell line of Catharanthus roseus (L.) G. Don to study the relative importance of the supply of biosynthetic precursors for the synthesis of terpenoid indole alkaloids. Line S10 carries a recombinant, constitutively overexpressed version of the endogenous strictosidine synthase (Str) gene. Various concentrations and combinations of the substrate tryptamine and of loganin, the immediate precursor of secologanin, were added to suspension cultures of S10. Our results indicate that high rates of tryptamine synthesis can take place under conditions of low tryptophan decarboxylase activity, and that high rates of strictosidine synthesis are possible in the presence of a small tryptamine pool. It appears that the utilization of tryptamine for alkaloid biosynthesis enhances metabolic flux through the indole pathway. However, a deficiency in the supply of either the iridoid or the indole precursor can limit flux through the step catalyzed by strictosidine synthase. Precursor utilization for the synthesis of strictosidine depends on the availability of the cosubstrate; the relative abundance of these precursors is a cell-line-specific trait that reflects the metabolic status of the cultures.

Opium poppy and Madagascar periwinkle: model non‐model systems to investigate alkaloid biosynthesis in plants

“…Transgenic C. roseus cell cultures over-expressing TDC and/or STR1 did not produce higher levels of MIAs compared with controls Whitmer et al, 1998). Further experimentation suggested limited precursor availability as supplementation with loganin and tryptamine facilitated an increase in alkaloid accumulation.…”

Effects of PEG-induced drought stress on regulation of indole alkaloid biosynthesis in Catharanthus roseus

“…Currently, chemical synthesis and metabolic engineering plant cell or tissue culture (Whitmer et al 1998;Hughes & Shanks 2002) are alternative methods for the synthesis and production of TIAs. However, its low productivity and high cost (Rischer et al 2006;Mujib et al 2014) still hamper the development of industrial-scale production.…”

Geraniol 10‐hydroxylase1, a cytochrome P450 enzyme involved in terpenoid indole alkaloid biosynthesis

“…Strictosidine is the branch point from which biosynthesis routes diverge towards the various alkaloids found in di¡erent TIA-producing plant species [2,3]. Several studies using Catharanthus roseus indicate that the formation of secologanin can be a limiting factor in TIA production [4,5]. G10H was suggested to have a regulatory e¡ect on alkaloid production [6,7].…”