title: Improving peppermint essential oil yield and composition by metabolic engineering.
abstract: Peppermint (Mentha × piperita L.) was transformed with various gene constructs to evaluate the utility of metabolic engineering for improving essential oil yield and composition. Oil yield increases were achieved by overexpressing genes involved in the supply of precursors through the 2C-methyl-D-erythritol 4-phosphate (MEP) pathway. Two-gene combinations to enhance both oil yield and composition in a single transgenic line were assessed as well. The most promising results were obtained by transforming plants expressing an antisense version of (+)-menthofuran synthase, which is critical for adjusting the levels of specific undesirable oil constituents, with a construct for the overexpression of the MEP pathway gene 1-deoxy-D-xylulose 5-phosphate reductoisomerase (up to 61% oil yield increase over wild-type controls with low levels of the undesirable side-product (+)-menthofuran and its intermediate (+)-pulegone). Elite transgenic lines were advanced to multiyear field trials, which demonstrated consistent oil yield increases of up to 78% over wild-type controls and desirable effects on oil composition under commercial growth conditions. The transgenic expression of a gene encoding (+)-limonene synthase was used to accumulate elevated levels of (+)-limonene, which allows oil derived from transgenic plants to be recognized during the processing of commercial formulations containing peppermint oil. Our study illustrates the utility of metabolic engineering for the sustainable agricultural production of high quality essential oils at a competitive cost.
authors.affiliation: Institute of Biological Chemistry and MJ Murdock Metabolomics Laboratory, Washington State University, Pullman, WA 99164-6340, USA.
authors.forename: Bernd Markus
authors.initials: BM
authors.lastname: Lange
authors.forename: Soheil Seyed
authors.initials: SS
authors.lastname: Mahmoud
authors.forename: Mark R
authors.initials: MR
authors.lastname: Wildung
authors.forename: Glenn W
authors.initials: GW
authors.lastname: Turner
authors.forename: Edward M
authors.initials: EM
authors.lastname: Davis
authors.forename: Iris
authors.initials: I
authors.lastname: Lange
authors.forename: Raymond C
authors.initials: RC
authors.lastname: Baker
authors.forename: Rick A
authors.initials: RA
authors.lastname: Boydston
authors.forename: Rodney B
authors.initials: RB
authors.lastname: Croteau
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D015415:Biomarkers / Q000032:analysis; D053138:Cyclohexenes / Q000032:analysis; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D017343:Genes, Plant; D019753:Intramolecular Lyases / Q000235:genetics / Q000378:metabolism; D000077222:Limonene; D036142:Mentha piperita / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D060847:Metabolic Engineering / Q000379:methods; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D010938:Plant Oils / Q000737:chemistry / Q000302:isolation & purification*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D060888:Real-Time Polymerase Chain Reaction; D013729:Terpenes / Q000032:analysis
chemical_list: D015415:Biomarkers; D053138:Cyclohexenes; D017931:DNA Primers; D009097:Multienzyme Complexes; D010938:Plant Oils; D010940:Plant Proteins; D013729:Terpenes; D003577:Cytochrome P-450 Enzyme System; D000077222:Limonene; C015424:peppermint oil; D010088:Oxidoreductases; C114231:1-deoxy-D-xylulose 5-phosphate reductoisomerase; C430094:menthofuran synthase; D019747:Aldose-Ketose Isomerases; D019753:Intramolecular Lyases; C040265:pinene cyclase I