title: Identification and characterization of a second isogene encoding γ-terpinene synthase in Thymus caespititius.
abstract: Thymus caespititius Brot. is an Iberian endemic species, whose essential oils possess high polymorphism. They consist mostly of mono- and sesquiterpene, some of them with interest for the pharmaceutical and food industries. The search for terpene synthase genes was performed in three in vitro T. caespititius genotypes. For these plants, the expression of a previously described γ-terpinene synthase gene, Tctps2, was confirmed, occurring concomitantly with a new gene encoding an enzyme with similar activity, named Thymus caespititius terpene synthase 4 (Tctps4). The two isogenes were isolated and functionally characterized in the three plant genotypes. Alignment of the two Tctps revealed a transit peptide much shorter in Tctps4 than in Tctps2 (3-4 amino acids instead of 47). The Tctps4 open reading frame is shorter than Tctps2 (1665 bp versus 1794 bp). The amino acid sequence of both γ-terpinene synthases shared an 88% pairwise identity. The fact that T. caespititius carries two isogenes for γ-terpinene synthases, suggests gene duplication along the evolutionary process, followed by mutations leading to the differentiation of both genes. These mutations didn't compromise protein activity. A high accumulation of transcripts from both genes was found in shoots of in vitro plantlets, while in roots they could not be detected. Still, γ-terpinene levels in aerial parts were reduced, probably due to fast conversion into carvacrol and thymol, the main components from T. caespititius essential oils. This study is a contribution to the identification of terpene synthase genes in Lamiaceae.
authors: Universidade de Lisboa, Faculdade de Ciências de Lisboa, Departamento de Biologia Vegetal, Instituto de Biotecnologia e Bioengenharia, Centro de Biotecnologia Vegetal, C2, Piso 1, Campo Grande, 1749-016 Lisboa, Portugal.
authors: Marta D
authors: MD
authors: Mendes
authors: Universidade de Lisboa, Faculdade de Ciências de Lisboa, Departamento de Biologia Vegetal, Instituto de Biotecnologia e Bioengenharia, Centro de Biotecnologia Vegetal, C2, Piso 1, Campo Grande, 1749-016 Lisboa, Portugal.
authors: José G
authors: JG
authors: Barroso
authors: Instituto de Tecnologia Química e Biológica (ITQB-UNL), Av. da República, 2780-157 Oeiras, Portugal.
authors: M Margarida
authors: MM
authors: Oliveira
authors: Universidade de Lisboa, Faculdade de Ciências de Lisboa, Departamento de Biologia Vegetal, Instituto de Biotecnologia e Bioengenharia, Centro de Biotecnologia Vegetal, C2, Piso 1, Campo Grande, 1749-016 Lisboa, Portugal. Electronic address: htrindade@fc.ul.pt.
authors: Helena
authors: H
authors: Trindade
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D002849:Chromatography, Gas; D000081005:Cyclohexane Monoterpenes; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008969:Molecular Sequence Data; D039821:Monoterpenes / Q000378:metabolism*; D009822:Oils, Volatile / Q000378:metabolism; D010802:Phylogeny; D018520:Plant Shoots / Q000201:enzymology / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D046930:Thymus Plant / Q000201:enzymology* / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D000081005:Cyclohexane Monoterpenes; D039821:Monoterpenes; D009822:Oils, Volatile; D012333:RNA, Messenger; C018669:gamma-terpinene; D019883:Alkyl and Aryl Transferases; C108877:terpene synthase
keywords: Chemotypes; In vitro culture; Lamiaceae; Monoterpene; Terpene synthases