Open Collections

Cloning of lavandula essential oil biosynthetic genes

University of British Columbia

Several varieties of Lavandula x intermedia (lavandins) are cultivated for their essential oils (EO) which are extensively used in a wide range of hygiene and personal care products. These EOs are mainly dominated by monoterpenes, including linalool, linalool acetate, borneol, 1,8-cineole, and camphor. Among these, camphor is of particular significance as it adds a sharp overtone to the EO fragrance, reducing its olfactory appeal compared to finer lavender EOs in which linalool and linalool acetate impart a pleasant scent. We have recently constructed a cDNA library from the secretory cells of floral glandular trichomes of L. x intermedia plants. In this thesis we describe the cloning of a borneol dehydrogenase (LiBDH), a putative linalool acetyltransferase (LiLAT), and a caryophyllene synthase (LiCPS) cDNA from this library. The 780 bp open reading frame (ORF) of the LiBDH cDNA encoded a 259 amino acid short chain alcohol dehydrogenase enzyme with a predicted molecular mass of ca. 27.5 kDa. The recombinant LiBDH was expressed in E. coli, purified by Ni- NTA agarose affinity chromatography, and functionally characterized. The bacterially produced enzyme specifically converted borneol to camphor as the only product with Km and kcat values of 53 μM and 4.0x 10-⁴ s-¹, respectively. The LiBDH transcripts were detected both in leaf and flower tissues. However, they were concentrated in floral glandular trichomes of mature L. x intermedia flowers indicating that like other Lavandula monoterpene synthases the expression of this gene is regulated in a tissue-specific manner. Using the same procedures described above a putative sesquiterpene synthase (LiCPS) was also cloned and functionally characterized. LiCPS produced caryophyllene from fernesyl diphosphate (FPP), and α-terpieol, 1,8-cineiole, and a few other monoterpenes from geranyl diphosphate (GPP) and neryl diphosphate (NPP). Further, two additional lavender TPS’s, LiLAT and L. angustifolia terpene synthase like protien-I (LaTPS-I), were expressed in bacteria and assayed. Purified recombinant LiLAT and LaTPS-I, however, did not produce detectable amounts of any product in vitro.

Text

2013-09-01

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/43964

Biology

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/