Methylerythritol and Mevalonate Pathway Contributions to Biosynthesis of Mono-, Sesqui-, and Diterpenes in Glandular Trichomes and Leaves of Stevia rebaudiana Bertoni

Abstract

The biosynthesis of the diterpenoid steviol glycosides rebaudioside A and stevioside in nonrooted cuttings of Stevia rebaudiana was investigated by feeding experiments using the labeled key precursors [5,5-(2)H2]-mevalonic acid lactone (d2-MVL) and [5,5-(2)H2]-1-deoxy-d-xylulose (d2-DOX). Labeled glycosides were extracted from the leaves and stems and were directly analyzed by LC-(-ESI)-MS/MS and by GC-MS after hydrolysis and derivatization of the resulting isosteviol to the corresponding TMS-ester. Additionally, the incorporation of the proffered d2-MVL and d2-DOX into volatile monoterpenes, sesquiterpenes, and diterpenes in glandular trichomes on leaves and stems was investigated by headspace-solid phase microextraction-GC-MS (HS-SPME-GC-MS). Incorporation of the labeled precursors indicated that diterpenes in leaves and monoterpenes and diterpenes in glandular trichomes are predominately biosynthesized via the methylerythritol phosphate (MEP) pathway, whereas both the MEP and mevalonate (MVA) pathways contribute to the biosynthesis of sesquiterpenes at equal rates in glandular trichomes. These findings give evidence for a transport of MEP pathway derived farnesyl diphosphate precursors from plastids to the cytosol. Contrarily, the transport of MVA pathway derived geranyl diphosphate and geranylgeranyl diphosphate precursors from the cytosol to the plastid is limited.

Molecular Cloning and Characterization of DXS and DXR Genes in the Terpenoid Biosynthetic Pathway of Tripterygium wilfordii

“…The biosynthesis of terpenoids includes the common precursor substance isopentenyl diphosphate (IPP) and its isomer dimethylallyl diphosphate (DMAPP), which are generated through two pathways: the mevalonate (MVA) pathway and the methylerythritol phosphate (MEP) pathway [ 12 ]. The MEP pathway is principally involved in providing isoprenoids for monoterpenes [ 13 ], diterpenes [ 14 ] and carotenoids [ 15 ]. The 1-deoxy- d -xylulose-5-phosphate synthase ( DXS ) and 1-deoxy- d -xylulose-5-phosphate reductoisomerase ( DXR ) genes are the first two rate-limiting enzyme genes in this pathway.…”

Seaweeds as Source of New Bioactive Prototypes

“…Additionally, species of Rhodophyta are skilled in the incorporation of chlorine and bromine atoms. The monoterpenes are substances with ten carbons formed by two isoprene units, and can be cyclic or aliphatic (acyclic) [68]. Halogenated monoterpenes are found in genres Plocamium, Portieria, and Ochtodes [69].…”

A 1-deoxy-d-xylulose 5-phosphate reductoisomerase gene probably involved in the synthesis of terpenoids in Chrysanthemum indicum var. aromaticum

“…Terpenoids are a class of compounds, including all the isoprene polymers and their derivatives, constructed using isoprene as the basic building block. At present, the majority of terpenoids are known to be synthesized by two biosynthetic pathways: the mevalonate (MVA) pathway and the plastid-localized 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway (Wölwer-Rieck et al 2014). The MEP pathway is principally involved in providing isoprenoids for monoterpenes (Lange et al 2000), sesquiterpenes (Dudareva et al 2005), diterpenes (Ge and Wu 2005), and carotenoids (Lu et al 2012).…”