Terpene Moiety Enhancement by Overexpression of Geranyl(geranyl) Diphosphate Synthase and Geraniol Synthase Elevates Monomeric and Dimeric Monoterpene Indole Alkaloids in Transgenic Catharanthus roseus

Abstract

Catharanthus roseus is the sole source of two of the most important anticancer monoterpene indole alkaloids (MIAs), vinblastine and vincristine and their precursors, vindoline and catharanthine. The MIAs are produced from the condensation of precursors derived from indole and terpene secoiridoid pathways. It has been previously reported that the terpene moiety limits MIA biosynthesis in C. roseus. Here, to overcome this limitation and enhance MIAs levels in C. roseus, bifunctional geranyl(geranyl) diphosphate synthase [G(G)PPS] and geraniol synthase (GES) that provide precursors for early steps of terpene moiety (secologanin) formation, were overexpressed transiently by agroinfiltration and stably by Agrobacterium-mediated transformation. Both transient and stable overexpression of G(G)PPS and co-expression of G(G)PPS+GES significantly enhanced the accumulation of secologanin, which in turn elevated the levels of monomeric MIAs. In addition, transgenic C. roseus plants exhibited increased levels of root alkaloid ajmalicine. The dimeric alkaloid vinblastine was enhanced only in G(G)PPS but not in G(G)PPS+GES transgenic lines that correlated with transcript levels of peroxidase-1 (PRX1) involved in coupling of vindoline and catharanthine into 3′,4′-anhydrovinblastine, the immediate precursor of vinblastine. Moreover, first generation (T1) lines exhibited comparable transcript and metabolite levels to that of T0 lines. In addition, transgenic lines displayed normal growth similar to wild-type plants indicating that the bifunctional G(G)PPS enhanced flux toward both primary and secondary metabolism. These results revealed that improved availability of early precursors for terpene moiety biosynthesis enhanced production of MIAs in C. roseus at the whole plant level. This is the first report demonstrating enhanced accumulation of monomeric and dimeric MIAs including root MIA ajmalicine in C. roseus through transgenic approaches.

De novo transcriptome assembly for the five major organs of Zanthoxylum armatum and the identification of genes involved in terpenoid compound and fatty acid metabolism

“…Moreover, Cluster-12,235.40340 was annotated to geranyl-geranyl diphosphate synthase 12 (GGPPS12). GGPPS is composed of an inactive small subunit and an active large subunit and generates important substrates associated with the biosynthesis of monoterpene compounds in various plants [35][36][37]. ZaTPS03 (Cluster-12,235.42010) was also identified in this study, which related to a typical monoterpene synthase that catalyses the transformation GPP into limonene as well as other related compounds [22].…”

Role of Secondary Metabolites to Attenuate Stress Damages in Plants

“…The diverse chemical structures of the SMs determine their functions to the medicine and stress adaptation. Three major categories are (i) terpenes derived from mevalonic acid pathway [25] and methyl erythritol phosphate pathway [26], (ii) phenolics derived from malonic acid pathway or a few case shikimic acid pathway [27], (iii) N (Nitrogen) and S (Sulfur) containing compounds via tricarboxylic acid cycle or sometimes via shikimic acid pathway. Among the pathways of SMs accumulation, shikimic acid, mevalonic acid, phenylpropanoic acid and methyl erythritol phosphate pathways are highly regulated under stress stimuli.…”

Strategies for the production of biochemicals in bioenergy crops

“…In tomato fruits, co-expression of a noncatalytic small subunit of GPPS (GPPS-SSU) from snapdragon and ObGES from basil (Ocimum basilicum) enhanced the production of geraniol 6.9-and 19.2-fold compared to the ObGES and GPPS-SSU parental lines, respectively [258]. Similarly, in Catharanthus roseus, accumulation of secologanin, a geraniol derived-monoterpene indole alkaloid, was achieved upon overexpression of CrGES along with a bifunctional CrG(G)PPS [259,260]. In addition, a combinatorial production of geraniol in tobacco has been examined using different subcellular compartments (i.e., plastids, cytosol or mitochondria): results showed that plastid-targeted VoGES combined with expression GPPS from Picea abies (PaGDPS1) for GPP overproduction lead to the highest production of geraniol [261].…”