Abstract
Vanda Mimi Palmer (VMP), an orchid hybrid of Vanda tesselata and Vanda Tan Chay Yan is a highly scented tropical orchid which blooms all year round. Previous studies revealed that VMP produces a variety of isoprenoid volatiles during daylight. Isoprenoids are well known to contribute significantly to the scent of most fragrant plants. They are a large group of secondary metabolites which may possess valuable characteristics such as flavor, fragrance and toxicity and are produced via two pathways, the mevalonate (MVA) pathway or/and the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway. In this study, a sesquiterpene synthase gene denoted VMPSTS, previously isolated from a floral cDNA library of VMP was cloned and expressed in Lactococcus lactis to characterize the functionality of the protein. L. lactis, a food grade bacterium which utilizes the mevalonate pathway for isoprenoid production was found to be a suitable host for the characterization of plant terpene synthases. Through recombinant expression of VMPSTS, it was revealed that VMPSTS produced multiple sesquiterpenes and germacrene D dominates its profile.
Highlights
Isoprenoids are a large and diverse class of naturally occurring metabolites
We report on the functional expression of a sesquiterpene synthase gene from
The sesquiterpene synthase from Vanda Mimi Palmer, previously isolated by Chan et al [23] was successfully cloned into pNZ8048 yielding pNZ:VMPSTS
Summary
While all organisms produce isoprenoids such as prenyl lipids for cell membrane synthesis and ubiquinone for electron transport as part of their primary metabolism [1], many produce isoprenoids as secondary metabolites with valuable characteristics such as flavor, fragrance, toxicity and medicinal properties. Since prokaryotes possess the necessary metabolic pathways involved in isoprenoid production, plant terpene synthases cloned into prokaryotes enable them to produce plant isoprenoids in vivo This can be carried out by utilization of the host’s precursors such as geranyl pyrophosphate (GPP) and farnesyl pyrophosphate (FPP) for the production of mono- and sesquiterpenes respectively, provided that the pool of precursors is sufficient to maintain the requirements of both the endogenous pathways as well as the fabricated one. L. lactis was shown to be a potential host for heterologous isoprenoid production, sesquiterpenes, concurring with findings by Hernandez et al [20]
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