title: Formation of norisoprenoid flavor compounds in carrot (Daucus carota L.) roots: characterization of a cyclic-specific carotenoid cleavage dioxygenase 1 gene.
abstract: Carotenoids are isoprenoid pigments that upon oxidative cleavage lead to the production of norisoprenoids that have profound effect on flavor and aromas of agricultural products. The biosynthetic pathway to norisoprenoids in carrots (Daucus carota L.) is still largely unknown. We found the volatile norisoprenoids farnesylacetone, α-ionone, and β-ionone accumulated in Nairobi, Rothild, and Purple Haze cultivars but not in Yellowstone and Creme de Lite in a pattern reflecting their carotenoid content. A cDNA encoding a protein with carotenoid cleavage dioxygenase activity, DcCCD1, was identified in carrot and was overexpressed in Escherichia coli strains previously engineered to produce different carotenoids. The recombinant DcCCD1 enzyme cleaves cyclic carotenes to generate α- and β-ionone. No cleavage products were found when DcCCD1 was co-expressed in E. coli strains accumulating non-cyclic carotenoids, such as phytoene or lycopene. Our results suggest a role for DcCCD1 in carrot flavor biosynthesis.
authors.affiliation: Newe Ya'ar Research Center, Agricultural Research Organization , Post Office Box 1021, Ramat Yishay 30095, Israel.
authors.forename: Mosaab
authors.initials: M
authors.lastname: Yahyaa
authors.forename: Einat
authors.initials: E
authors.lastname: Bar
authors.forename: Neeraj Kumar
authors.initials: NK
authors.lastname: Dubey
authors.forename: Ayala
authors.initials: A
authors.lastname: Meir
authors.forename: Rachel
authors.initials: R
authors.lastname: Davidovich-Rikanati
authors.forename: Joseph
authors.initials: J
authors.lastname: Hirschberg
authors.forename: Radi
authors.initials: R
authors.lastname: Aly
authors.forename: Dorothea
authors.initials: D
authors.lastname: Tholl
authors.forename: Philipp W
authors.initials: PW
authors.lastname: Simon
authors.forename: Yaakov
authors.initials: Y
authors.lastname: Tadmor
authors.forename: Efraim
authors.initials: E
authors.lastname: Lewinsohn
authors.forename: Mwafaq
authors.initials: M
authors.lastname: Ibdah
mesh_terms: D018552:Daucus carota / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D049308:Dioxygenases / Q000235:genetics / Q000378:metabolism*; D005421:Flavoring Agents / Q000378:metabolism*; D045792:Norisoprenoids / Q000096:biosynthesis*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D005421:Flavoring Agents; D045792:Norisoprenoids; D010940:Plant Proteins; D049308:Dioxygenases; C431939:carotenoid cleavage dioxygenase 1