title: A petunia chorismate mutase specialized for the production of floral volatiles.
abstract: In Petunia x hybrida cv. 'Mitchell Diploid' floral fragrance is comprised of 13 volatile benzenoids/phenylpropanoids derived from the aromatic amino acid phenylalanine. Several genes involved in the direct synthesis of individual floral volatile benzenoid/phenylpropanoid (FVBP) compounds, i.e. at the end of the pathway, have been isolated and characterized in petunia through reverse genetic and biochemical approaches. In an effort to understand the regulation of 'upstream' components in the FVBP system, we have cloned and characterized two CHORISMATE MUTASE (PhCM1 and PhCM2) cDNAs from petunia. PhCM1 has a transcript accumulation profile consistent with known FVBP genes, while PhCM2 showed a constitutive transcript accumulation profile. The plastid-localized PhCM1 is allosterically regulated by tryptophan but not phenylalanine or tyrosine. The total FVBP emission in PhCM1 RNAi knockdown petunias is reduced by approximately 60-70%, and total chorismate mutase activity in corolla tissue is reduced by 80-85% compared to control plants. These results show that PhCM1 is the principal CHORISMATE MUTASE responsible for the coupling of metabolites from the shikimate pathway to the synthesis of FVBPs in the corolla of Petunia x hybrida cv. 'Mitchell Diploid'.
authors.affiliation: Department of Environmental Horticulture, and Plant Molecular and Cellular Biology, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Colquhoun
authors.forename: Bernardus C J
authors.initials: BC
authors.lastname: Schimmel
authors.forename: Joo Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Didier
authors.initials: D
authors.lastname: Reinhardt
authors.forename: Kenneth
authors.initials: K
authors.lastname: Cline
authors.forename: David G
authors.initials: DG
authors.lastname: Clark
mesh_terms: D001555:Benzene Derivatives / Q000737:chemistry / Q000378:metabolism; D002826:Chorismate Mutase / Q000235:genetics / Q000502:physiology*; D035264:Flowers / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D008954:Models, Biological; D032306:Petunia / Q000201:enzymology*; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology*; D020005:Propanols / Q000737:chemistry / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012765:Shikimic Acid / Q000737:chemistry / Q000378:metabolism; D055549:Volatile Organic Compounds / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D001555:Benzene Derivatives; D010940:Plant Proteins; D020005:Propanols; D055549:Volatile Organic Compounds; D012765:Shikimic Acid; D002826:Chorismate Mutase