title: Volatile squalene from a nonseed plant Selaginella moellendorffii: Emission and biosynthesis.
abstract: The triterpene squalene is a key metabolic intermediate for sterols, hopanoids and various other triterpenoids. The biosynthesis of squalene is catalyzed by squalene synthase (SQS), which converts two molecules of farnesyl diphosphate to squalene. In this study, a lycophyte Selaginella moellendorffii was found to emit squalene as a volatile compound under a number of conditions that mimic biotic stresses. Searching the genome sequence of S. moellendorffii led to the identification of a putative squalene synthase gene. It was designated as SmSQS. SmSQS is homologous to known squalene synthases from other plants and animals at both the amino acid level and structural level. Recombinant SmSQS expressed in Escherichia coli catalyzed the formation of squalene using farnesyl diphosphate as substrate. The expression of SmSQS was significantly induced by the same set of stress factors that induced the emission of volatile squalene from S. moellendorffii plants. Taken together, these results support that SmSQS is responsible for the biosynthesis of volatile squalene and volatile squalene may have a role in the defense of S. moellendorffii plants against biotic stresses.
authors.affiliation: Department of Plant Sciences, University of Tennessee, 252 Ellington Plant Science Bldg, 2431 Joe Johnson Drive, Knoxville, TN 37996, USA; College of Horticulture, Northwest Agricultural and Forestry University, Yangling, Shaanxi, 712100, China; College of Art, Changzhou University, Jiangsu, China.
authors.forename: Yifan
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Department of Plant Sciences, University of Tennessee, 252 Ellington Plant Science Bldg, 2431 Joe Johnson Drive, Knoxville, TN 37996, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Plant Sciences, University of Tennessee, 252 Ellington Plant Science Bldg, 2431 Joe Johnson Drive, Knoxville, TN 37996, USA.
authors.forename: Xinlu
authors.initials: X
authors.lastname: Chen
authors.affiliation: Max Planck Institute for Chemical Ecology, Hans-Knoell-Strasse 8, D-07745 Jena, Germany.
authors.forename: Tobias G
authors.initials: TG
authors.lastname: Köllner
authors.affiliation: Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Qidong
authors.initials: Q
authors.lastname: Jia
authors.affiliation: Department of Biochemistry, Cellular and Molecular Biology and UT/ORNL Center for Molecular Biophysics, University of Tennessee, Knoxville, TN 37996, USA.
authors.forename: Troy W
authors.initials: TW
authors.lastname: Wymore
authors.affiliation: College of Horticulture, Northwest Agricultural and Forestry University, Yangling, Shaanxi, 712100, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.affiliation: Department of Plant Sciences, University of Tennessee, 252 Ellington Plant Science Bldg, 2431 Joe Johnson Drive, Knoxville, TN 37996, USA; Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN 37996, USA. Electronic address: fengc@utk.edu.
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D055162:Biocatalysis; D004926:Escherichia coli / Q000235:genetics; D013186:Farnesyl-Diphosphate Farnesyltransferase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008958:Models, Molecular; D008969:Molecular Sequence Data; D032503:Selaginellaceae / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013185:Squalene / Q000378:metabolism*; D055549:Volatile Organic Compounds / Q000378:metabolism*
chemical_list: D055549:Volatile Organic Compounds; D013185:Squalene; D013186:Farnesyl-Diphosphate Farnesyltransferase
keywords: GC-MS; Lycophyte; Stress physiology; Terpenoid; Triterpene; Volatile