| Summary: | 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.
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