| Title: | (E)-beta-ocimene and myrcene synthase genes of floral scent biosynthesis in snapdragon: function and expression of three terpene synthase genes of a new terpene synthase subfamily |
| Author(s): | Dudareva N; Martin D; Kish CM; Kolosova N; Gorenstein N; Faldt J; Miller B; Bohlmann J; |
| Address: | "Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907, USA. dudareva@hort.purdue.edu" |
| ISSN/ISBN: | 1040-4651 (Print) 1532-298X (Electronic) 1040-4651 (Linking) |
| Abstract: | "Snapdragon flowers emit two monoterpene olefins, myrcene and (E)-beta-ocimene, derived from geranyl diphosphate, in addition to a major phenylpropanoid floral scent component, methylbenzoate. Emission of these monoterpenes is regulated developmentally and follows diurnal rhythms controlled by a circadian clock. Using a functional genomics approach, we have isolated and characterized three closely related cDNAs from a snapdragon petal-specific library that encode two myrcene synthases (ama1e20 and ama0c15) and an (E)-beta-ocimene synthase (ama0a23). Although the two myrcene synthases are almost identical (98%), except for the N-terminal 13 amino acids, and are catalytically active, yielding a single monoterpene product, myrcene, only ama0c15 is expressed at a high level in flowers and contributes to floral myrcene emission. (E)-beta-Ocimene synthase is highly similar to snapdragon myrcene synthases (92% amino acid identity) and produces predominantly (E)-beta-ocimene (97% of total monoterpene olefin product) with small amounts of (Z)-beta-ocimene and myrcene. These newly isolated snapdragon monoterpene synthases, together with Arabidopsis AtTPS14 (At1g61680), define a new subfamily of the terpene synthase (TPS) family designated the Tps-g group. Members of this new Tps-g group lack the RRx(8)W motif, which is a characteristic feature of the Tps-d and Tps-b monoterpene synthases, suggesting that the reaction mechanism of Tps-g monoterpene synthase product formation does not proceed via an RR-dependent isomerization of geranyl diphosphate to 3S-linalyl diphosphate, as shown previously for limonene cyclase. Analyses of tissue-specific, developmental, and rhythmic expression of these monoterpene synthase genes in snapdragon flowers revealed coordinated regulation of phenylpropanoid and isoprenoid scent production" |
| Keywords: | "Acyclic Monoterpenes Alkenes/*metabolism Alkyl and Aryl Transferases/*genetics/metabolism Amino Acid Sequence Antirrhinum/*enzymology/genetics/growth & development *Arabidopsis Proteins Circadian Rhythm/physiology Cloning, Molecular DNA, Complementary/che;" |
| Notes: | "MedlineDudareva, Natalia Martin, Diane Kish, Christine M Kolosova, Natalia Gorenstein, Nina Faldt, Jenny Miller, Barbara Bohlmann, Jorg eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. England 2003/05/02 Plant Cell. 2003 May; 15(5):1227-41. doi: 10.1105/tpc.011015" |
