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Front. Plant Sci. | doi: 10.3389/fpls.2018.01435

Functional analysis of four terpene synthases in rose-scented pelargonium cultivars (Pelargonium x hybridum) and evolution of scent in the Pelargonium genus

 Bernard BLEROT1,  Laure MARTINELLI2, Cécile PRUNIER2,  Denis SAINT-MARCOUX2, Sylvain LEGRAND3, Aurélie BONY2, Loïc SARRABERE2, Florence GROS2, Nicolas BOYER2, Jean-Claude CAISSARD2,  Sylvie Baudino2 and  Frédéric JULLIEN2*
  • 1International Flavors & Fragrances (IFF-LMR), France
  • 2FRE3727 Laboratoire de Biotechnologies Végétales Appliquées aux plantes aromatiques et médicinales (BVpam), France
  • 3CNRS UMR 8198, Université de Lille, France

Pelargonium genus contains about 280 species among which at least 30 species are odorant. Aromas produced by scented species are remarkably diverse such as rose, mint, lemon, nutmeg, ginger and many others scents. Amongst odorant species, rose-scented pelargoniums, also named pelargoniums rosat, are the most famous hybrids for their production of essential oil (EO), widely used by perfume and cosmetic industries. Although EO composition has been extensively studied, the underlying biosynthetic pathways and their regulation, most notably of terpenes, are largely unknown. To gain a better understanding of the terpene metabolic pathways in pelargonium rosat, we generated a transcriptome dataset of pelargonium leaf and used a candidate gene approach to functionally characterise four terpene synthases (TPS), including a geraniol synthase, a key enzyme responsible for the biosynthesis of the main rose-scented terpenes. We also report for the first time the characterisation of a novel sesquiterpene synthase catalysing the biosynthesis of 10-epi--eudesmol. We found a strong correlation between expression of the four genes encoding the respective TPSs and accumulation of the corresponding products in several pelargonium cultivars and species. Finally, using publically available RNA-Seq data and de novo transcriptome assemblies, we inferred a maximum likelihood phylogeny from 270 pelargonium TPSs, including the four newly discovered enzymes, providing clues about TPS evolution in the Pelargonium genus. Notably, we show that, by contrast to other TPSs, geraniol synthases from the TPS-g subfamily conserved their molecular function throughout evolution.

Keywords: Pelargonium, terpene synthase, Essential oil, G, eraniol synthase, Transcription, Genetic

Received: 23 May 2018; Accepted: 10 Sep 2018.

Edited by:

Danièle WERCK, Centre national de la recherche scientifique (CNRS), France

Reviewed by:

Ai-Xia Cheng, Shandong University, China
Eric Duchêne, Institut National de la Recherche Agronomique (INRA), France  

Copyright: © 2018 BLEROT, MARTINELLI, PRUNIER, SAINT-MARCOUX, LEGRAND, BONY, SARRABERE, GROS, BOYER, CAISSARD, Baudino and JULLIEN. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Frédéric JULLIEN, FRE3727 Laboratoire de Biotechnologies Végétales Appliquées aux plantes aromatiques et médicinales (BVpam), St Etienne, France, jullien@univ-st-etienne.fr