title: Scent evolution in Chinese roses.
abstract: The phenolic methyl ether 3,5-dimethoxytoluene (DMT) is a major scent compound of many modern rose varieties, and its fragrance participates in the characteristic "tea scent" that gave their name to Tea and Hybrid Tea roses. Among wild roses, phenolic methyl ether (PME) biosynthesis is restricted to Chinese rose species, but the progenitors of modern roses included both European and Chinese species (e.g., Rosa chinensis cv Old Blush), so this trait was transmitted to their hybrid progeny. The last steps of the biosynthetic pathways leading to DMT involve two methylation reactions catalyzed by the highly similar orcinol O-methyltransferases (OOMT) 1 and 2. OOMT1 and OOMT2 enzymes exhibit different substrate specificities that are consistent with their operating sequentially in DMT biosynthesis. Here, we show that these different substrate specificities are mostly due to a single amino acid polymorphism in the phenolic substrate binding site of OOMTs. An analysis of the OOMT gene family in 18 species representing the diversity of the genus Rosa indicated that only Chinese roses possess both the OOMT2 and the OOMT1 genes. In addition, we provide evidence that the Chinese-rose-specific OOMT1 genes most probably evolved from an OOMT2-like gene that has homologues in the genomes of all extant roses. We propose that the emergence of the OOMT1 gene may have been a critical step in the evolution of scent production in Chinese roses.
authors.affiliation: Institut Fédératif de Recherche 128, Unité Mixte de Recherche 5667, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université Lyon 1, Ecole Normale Supérieure de Lyon, France.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Scalliet
authors.forename: Florence
authors.initials: F
authors.lastname: Piola
authors.forename: Christophe J
authors.initials: CJ
authors.lastname: Douady
authors.forename: Stéphane
authors.initials: S
authors.lastname: Réty
authors.forename: Olivier
authors.initials: O
authors.lastname: Raymond
authors.forename: Sylvie
authors.initials: S
authors.lastname: Baudino
authors.forename: Karim
authors.initials: K
authors.lastname: Bordji
authors.forename: Mohammed
authors.initials: M
authors.lastname: Bendahmane
authors.forename: Christian
authors.initials: C
authors.lastname: Dumas
authors.forename: J Mark
authors.initials: JM
authors.lastname: Cock
authors.forename: Philippe
authors.initials: P
authors.lastname: Hugueney
mesh_terms: D000840:Anisoles; D001483:Base Sequence; D005075:Biological Evolution; D002681:China; D005060:Europe; D035264:Flowers; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics*; D008969:Molecular Sequence Data; D009812:Odorants / Q000032:analysis*; D011110:Polymorphism, Genetic; D027826:Rosa; D013379:Substrate Specificity / Q000235:genetics
chemical_list: D000840:Anisoles; C465201:3,5-dimethoxytoluene; D008780:Methyltransferases