Trichome specific expression of tobacco (Nicotiana sylvestris) cembratrien-ol synthase genes is controlled by both activating and repressing cis-regions

Laboratoire d'Ecologie Alpine, Université Joseph Fourier and CNRS-Unité Mixte de Recherche 5553, 2233, rue de piscine, BP 53, 38041 Grenoble Cedex 9, France.
Plant Molecular Biology (Impact Factor: 4.26). 08/2010; 73(6):673-85. DOI: 10.1007/s11103-010-9648-x
Source: PubMed

ABSTRACT Tobacco (Nicotiana sylvestris) glandular trichomes make an attractive target for isoprenoid metabolic engineering because they produce large amounts of one type of diterpenoids, alpha- and beta-cembratrien-diols. This article describes the establishment of tools for metabolic engineering of tobacco trichomes, namely a transgenic line with strongly reduced levels of diterpenoids in the exudate and the characterization of a trichome specific promoter. The diterpene-free tobacco line was generated by silencing the major tobacco diterpene synthases, which were found to be encoded by a family of four highly similar genes (NsCBTS-2a, NsCBTS-2b, NsCBTS-3 and NsCBTS-4), one of which is a pseudogene. The promoter regions of all four CBTS genes were sequenced and found to share over 95% identity between them. Transgenic plants expressing uidA under the control of the NsCBTS-2a promoter displayed a specific pattern of GUS expression restricted exclusively to the glandular cells of the tall secretory trichomes. A series of sequential and internal deletions of the NsCBTS-2a promoter led to the identification of two cis-acting regions. The first, located between positions -589 to -479 from the transcription initiation site, conferred a broad transcriptional activation, not only in the glandular cells, but also in cells of the trichome stalk, as well as in the leaf epidermis and the root. The second region, located between positions -279 to -119, had broad repressor activity except in trichome glandular cells and is mainly responsible for the specific expression pattern of the NsCBTS-2a gene. These results establish the basis for the identification of trans-regulators required for the expression of the CBTS genes restricted to the secretory cells of the glandular trichomes.

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Available from: Gilles Vachon, Nov 20, 2014
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    • "In both apple and transgenic tobacco, the MdAAT2 promoter was highly active in stigmas and also in the glandular trichomes of transgenic tobacco leaves and sepals (Fig. 5a, b; Supplementary Fig. S3). Glandular trichomes are specialized organs located on the surface of the aerial parts of many higher plant species, and these structures have been shown to produce an abundance of secondary metabolites in certain species (Ennajdaoui et al. 2010; Wagner et al. 2004). Moreover, esters could be detected in apple leaves, and some ester compounds were only detected during phytophagous mite attack (Llusia and Penuelas 2001). "
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    Plant Molecular Biology 06/2014; 85(6). DOI:10.1007/s11103-014-0207-8 · 4.26 Impact Factor
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    • "TpGAS was found to be expressed much higher in the trichomes compared in the other tissues (Majdi et al., 2011). Trichome specific expression of a diterpene synthase in transgenic tobacco was recently reported (Ennajdaoui et al., 2010). To obtain higher production of free parthenolide in heterologous plants host, it would be a good option to try tissue specific expression in trichomes to prevent conjugation. "
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    • "To test N. benthamiana as a transient expression system for the production of plant diterpenes, we chose the cembratrien-ol (CBT-ol) synthase encoded by the trichome-specific NsCBTS2a gene from Nicotiana sylvestris[33]. CBTS enzymes from tobacco are class I terpene synthases which directly cyclize GGPP to a mixture of α- and β-CBT-ol. "
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