Dynamics of Monoterpene Formation in Spike Lavender Plants.

Isabel Mendoza-Poudereux,Erika Kutzner,Isabel Arrillaga,Wolfgang Eisenreich,Juan Segura,Claudia Huber

doi:10.3390/metabo7040065

Isabel Mendoza-Poudereux, Erika Kutzner + Show 4 more

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https://doi.org/10.3390/metabo7040065

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Abstract

The metabolic cross-talk between the mevalonate (MVA) and the methylerythritol phosphate (MEP) pathways was analyzed in spike lavender (Lavandula latifolia Med) on the basis of 13CO2-labelling experiments using wildtype and transgenic plants overexpressing the 3-hydroxy-3-methylglutaryl CoA reductase (HMGR), the first and key enzyme of the MVA pathway. The plants were labelled in the presence of 13CO2 in a gas chamber for controlled pulse and chase periods of time. GC/MS and NMR analysis of 1,8-cineole and camphor, the major monoterpenes present in their essential oil, indicated that the C5-precursors, isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) of both monoterpenes are predominantly biosynthesized via the MEP pathway. Surprisingly, overexpression of HMGR did not have significant impact upon the crosstalk between the MVA and MEP pathways indicating that the MEP route is the preferred pathway for the synthesis of C5 monoterpene precursors in spike lavender.

Highlights

Terpenes are the largest and most diverse family of natural products
We describe the 13 CO2 labelling conditions necessary to study the incorporation of 13 CO2 into cineole and camphor in wild type (WT) and HMGR5 transgenic spike lavender plants
If the MVA pathway is involved, the ratios would rise above those numbers, because of the presence of more M+2 coming from isopentenyl diphosphate (IPP) from the cytosolic space

Summary

Introduction

Terpenes are the largest and most diverse family of natural products Within these compounds both primary metabolites (hormones, carotenoids, chlorophylls and sterols), necessary for plant growth and survival, and secondary metabolites, that are not directly involved in growth and/or development, can be found [1,2,3,4,5]. All terpenes originate from the universal C5 precursor IPP and its isomer DMAPP. In plants, both compounds are formed through two pathways [10,11]: the cytosolic MVA pathway, which comprises several enzymatic reactions from acetyl coenzymeA condensation through mevalonate iphosphate decarboxylation, and the plastidial MEP pathway starting from the reaction between pyruvate and glyceraldehyde-3-phosphate (Figure 1).

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