title: The floral transcriptome of ylang ylang (Cananga odorata var. fruticosa) uncovers biosynthetic pathways for volatile organic compounds and a multifunctional and novel sesquiterpene synthase.
abstract: The pleasant fragrance of ylang ylang varieties (Cananga odorata) is mainly due to volatile organic compounds (VOCs) produced by the flowers. Floral scents are a key factor in plant-insect interactions and are vital for successful pollination. C. odorata var. fruticosa, or dwarf ylang ylang, is a variety of ylang ylang that is popularly grown in Southeast Asia as a small shrub with aromatic flowers. Here, we describe the combined use of bioinformatics and chemical analysis to discover genes for the VOC biosynthesis pathways and related genes. The scented flowers of C. odorata var. fruticosa were analysed by gas chromatography/mass spectrometry and a total of 49 VOCs were identified at four different stages of flower development. The bulk of these VOCs were terpenes, mainly sesquiterpenes. To identify the various terpene synthases (TPSs) involved in the production of these essential oils, we performed RNA sequencing on mature flowers. From the RNA sequencing data, four full-length TPSs were functionally characterized. In vitro assays showed that two of these TPSs were mono-TPSs. CoTPS1 synthesized four products corresponding to β-thujene, sabinene, β-pinene, and α-terpinene from geranyl pyrophosphate and CoTPS4 produced geraniol from geranyl pyrophosphate. The other two TPSs were identified as sesqui-TPSs. CoTPS3 catalysed the conversion of farnesyl pyrophosphate to α-bergamotene, whereas CoTPS2 was found to be a multifunctional and novel TPS that could catalyse the synthesis of three sesquiterpenes, β-ylangene, β-copaene, and β-cubebene. Additionally, the activities of the two sesqui-TPSs were confirmed in planta by transient expression of these TPS genes in Nicotiana benthamiana leaves by Agrobacterium-mediated infiltration.
authors.affiliation: Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604 School of Computing, National University of Singapore, Singapore 117417.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Jin
authors.affiliation: Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604.
authors.forename: Mi Jung
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604 Department of Biological Sciences, National University of Singapore, Singapore 117543.
authors.forename: Savitha
authors.initials: S
authors.lastname: Dhandapani
authors.affiliation: Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604.
authors.forename: Jessica Gambino
authors.initials: JG
authors.lastname: Tjhang
authors.affiliation: Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604.
authors.forename: Jun-Lin
authors.initials: JL
authors.lastname: Yin
authors.affiliation: School of Computing, National University of Singapore, Singapore 117417.
authors.forename: Limsoon
authors.initials: L
authors.lastname: Wong
authors.affiliation: Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604.
authors.forename: Rajani
authors.initials: R
authors.lastname: Sarojam
authors.affiliation: Laboratory of Plant Molecular Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
authors.forename: Nam-Hai
authors.initials: NH
authors.lastname: Chua
authors.affiliation: Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604 Department of Biological Sciences, National University of Singapore, Singapore 117543 jangi@tll.org.sg.
authors.forename: In-Cheol
authors.initials: IC
authors.lastname: Jang
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000378:metabolism*; D053898:Biosynthetic Pathways / Q000235:genetics*; D054362:Cananga / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D035264:Flowers / Q000235:genetics* / Q000254:growth & development; D018506:Gene Expression Regulation, Plant; D063990:Gene Ontology; D017343:Genes, Plant; D058977:Molecular Sequence Annotation; D009822:Oils, Volatile / Q000378:metabolism; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000378:metabolism; D017423:Sequence Analysis, RNA; D013347:Subcellular Fractions / Q000201:enzymology; D059467:Transcriptome / Q000235:genetics*; D055549:Volatile Organic Compounds / Q000378:metabolism*
chemical_list: D009822:Oils, Volatile; D012333:RNA, Messenger; D011994:Recombinant Proteins; D055549:Volatile Organic Compounds; D019883:Alkyl and Aryl Transferases; C108877:terpene synthase
keywords: Cananga odorata var. fruticosa; floral scent; terpene synthase; terpenes; volatile organic compounds; ylang ylang.; β-Copaene; β-cubebene; β-ylangene