title: A genomics resource for investigating regulation of essential oil production in Lavandula angustifolia.
abstract: We are developing Lavandula angustifolia (lavender) as a model system for investigating molecular regulation of essential oil (a mixture of mono- and sesquiterpenes) production in plants. As an initial step toward building the necessary 'genomics toolbox' for this species, we constructed two cDNA libraries from lavender leaves and flowers, and obtained sequence information for 14,213 high-quality expressed sequence tags (ESTs). Based on homology to sequences present in GenBank, our EST collection contains orthologs for genes involved in the 1-deoxy-D: -xylulose-5-phosphate (DXP) and the mevalonic acid (MVA) pathways of terpenoid biosynthesis, and for known terpene synthases and prenyl transferases. To gain insight into the regulation of terpene metabolism in lavender flowers, we evaluated the transcriptional activity of the genes encoding for 1-deoxy-D: -xylulose-5-phosphate synthase (DXS) and HMG-CoA reductase (HMGR), which represent regulatory steps of the DXP and MVA pathways, respectively, in glandular trichomes (oil glands) by real-time PCR. While HMGR transcripts were barely detectable, DXS was heavily expressed in this tissue, indicating that essential oil constituents are predominantly produced through the DXP pathway in lavender glandular trichomes. As anticipated, the linalool synthase (LinS)-the gene responsible for the production of linalool, a major constituent of lavender essential oil-was also strongly expressed in glands. Surprisingly, the most abundant transcript in floral glandular trichomes corresponded to a sesquiterpene synthase (cadinene synthase, CadS), although sesquiterpenes are minor constituents of lavender essential oils. This result, coupled to the weak activity of the MVA pathway (the main route for sesquiterpene production) in trichomes, indicates that precursor supply may represent a bottleneck in the biosynthesis of sesquiterpenes in lavender flowers.
authors.affiliation: Biology and Physical Geography, Irving K. Barber School of Arts and Sciences, University of British Columbia Okanagan, 3333 University Way, Kelowna, BC, V1V 1V7, Canada.
authors.forename: Alexander
authors.initials: A
authors.lastname: Lane
authors.forename: Astrid
authors.initials: A
authors.lastname: Boecklemann
authors.forename: Grant N
authors.initials: GN
authors.lastname: Woronuk
authors.forename: Lukman
authors.initials: L
authors.lastname: Sarker
authors.forename: Soheil S
authors.initials: SS
authors.lastname: Mahmoud
mesh_terms: D000080462:Acyclic Monoterpenes; D019295:Computational Biology; D020224:Expressed Sequence Tags; D035264:Flowers / Q000235:genetics / Q000378:metabolism; D023281:Genomics / Q000379:methods*; D027523:Lavandula / Q000235:genetics* / Q000378:metabolism*; D008798:Mevalonic Acid / Q000378:metabolism; D008954:Models, Biological; D039821:Monoterpenes / Q000378:metabolism; D009822:Oils, Volatile / Q000378:metabolism*; D010428:Pentosephosphates / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D016133:Polymerase Chain Reaction; D013729:Terpenes / Q000378:metabolism
chemical_list: C109460:1-deoxylulose 5-phosphate; D000080462:Acyclic Monoterpenes; D039821:Monoterpenes; D009822:Oils, Volatile; D010428:Pentosephosphates; D010940:Plant Proteins; D013729:Terpenes; C018584:linalool; D008798:Mevalonic Acid