Cosuppression of limonene-3-hydroxylase in peppermint promotes accumulation of limonene in the essential oil.
cDNA clones encoding limonene synthase and limonene-3-hydroxylase, both driven by the CaMV 35S promoter, were independently transformed into peppermint (Menthaxpiperita) to alter the production and disposition of (-)-limonene, the first committed intermediate of essential oil biosynthesis in this species. Although both genes were constitutively expressed in leaves of transformed plants, the corresponding enzyme activities were not significantly increased in the glandular trichome sites of essential oil biosynthesis; thus, there was no effect on oil yield or composition in the regenerated plants. Cosuppression of the hydroxylase gene, however, resulted in the accumulation of limonene (up to 80% of the essential oil compared to about 2% of the oil in wild type plants), without influence on oil yield. These results indicate that limonene does not impose negative feedback on the synthase, or apparently influence other enzymes of monoterpene biosynthesis in peppermint, and suggests that pathway engineering can be employed to significantly alter essential oil composition without adverse metabolic consequences.
Institute of Biological Chemistry, Washington State University, PO Box 646340, Pullman, WA 99164-6340, USA.
Soheil S
SS
Mahmoud
Matthew
M
Williams
Rodney
R
Croteau
D053138:Cyclohexenes; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D020868:Gene Silencing; D019753:Intramolecular Lyases / Q000235:genetics / Q000378:metabolism; D000077222:Limonene; D036142:Mentha piperita / Q000235:genetics / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D039821:Monoterpenes / Q000378:metabolism; D009822:Oils, Volatile / Q000737:chemistry / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D013729:Terpenes / Q000378:metabolism*; D014158:Transcription, Genetic; D014170:Transformation, Genetic
D053138:Cyclohexenes; D065607:Cytochrome P-450 Enzyme Inhibitors; D039821:Monoterpenes; D009822:Oils, Volatile; D013729:Terpenes; D003577:Cytochrome P-450 Enzyme System; D000077222:Limonene; D006899:Mixed Function Oxygenases; C120915:limonene-3-hydroxylase; D019753:Intramolecular Lyases; C040265:pinene cyclase I