Several varieties of Lavandula x intermedia (lavandins) are cultivated for their essential oils (EOs) for use in cosmetic, hygiene and personal care products. These EOs are mainly constituted of monoterpenes including camphor, which contributes an off odor reducing the olfactory appeal of the oil. We have recently constructed a cDNA library from the glandular trichomes (the sites of EO synthesis) of L. x intermedia plants. Here, we describe the cloning of a borneol dehydrogenase cDNA (LiBDH) from this library. The 780 bp open reading frame of the cDNA encoded a 259 amino acid short chain alcohol dehydrogenase with a predicted molecular mass of ca. 27.5 kDa. The recombinant LiBDH was expressed in Escherichia coli, purified by Ni-NTA agarose affinity chromatography, and functionally characterized in vitro. The bacterially produced enzyme specifically converted borneol to camphor as the only product with K(m) and k(cat) values of 53 μM and 4.0 × 10(-4) s(-1), respectively. The LiBDH transcripts were specifically expressed in glandular trichomes of mature flowers indicating that like other Lavandula monoterpene synthases the expression of this gene is regulated in a tissue-specific manner. The cloning of LiBDH has far reaching implications in improving the quality of Lavandula EOs through metabolic engineering.
Terpenoids are a large and diverse class of specialized metabolites that are essential for the growth and development of plants, and have tremendous industrial applications. The mericarps of Coriandrum sativum L. (coriander) produce an essential oil (EO) rich in monoterpenes, volatile C10 terpenoids. To investigate EO metabolism, the transcriptome of coriander mericarps, at three developmental stages (early, mid, late) was sequenced via Illumina technology and a transcript library was produced. To validate the usability of the transcriptome sequences, two terpene synthase candidate genes, CsγTRPS and CsLINS, encoding 558 and 562 amino acid proteins were expressed in bacteria, and the recombinant proteins purified by Ni-NTA affinity chromatography. The 65.16 (CsγTRPS) and 65.91 (CsLINS)kDa recombinant proteins catalyzed the conversion of geranyl diphosphate, the precursor to monoterpenes, to γ-terpinene and (S)-linalool, respectively, with apparent Vmax and Km values of 2.24±0.16 (CsγTRPS); 19.63±1.05 (CsLINS)pkat/mg and 66.25±13 (CsγTRPS); 2.5±0.6 (CsLINS)μM, respectively. Together, CsγTRPS and CsLINS account for the majority of EO constituents in coriander mericarps. Investigation of the coriander transcriptome, and knowledge gained from these experiments will facilitate future studies concerning essential and fatty acid oil production in coriander. They also enable efforts to improve the coriander oils through metabolic engineering or plant breeding.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.