Yahyaa, M., Newe ya'Ar Research Center, Agricultural Research Organization, Post Office Box 1021, Ramat Yishay 30095, Israel
Bar, E., Newe ya'Ar Research Center, Agricultural Research Organization, Post Office Box 1021, Ramat Yishay 30095, Israel
Dubey, N.K., Newe ya'Ar Research Center, Agricultural Research Organization, Post Office Box 1021, Ramat Yishay 30095, Israel
Meir, A., Newe ya'Ar Research Center, Agricultural Research Organization, Post Office Box 1021, Ramat Yishay 30095, Israel
Davidovich-Rikanati, R., Newe ya'Ar Research Center, Agricultural Research Organization, Post Office Box 1021, Ramat Yishay 30095, Israel
Hirschberg, J., Department of Genetics, Hebrew University of Jerusalem, Jerusalem 91904, Israel
Aly, R., Newe ya'Ar Research Center, Agricultural Research Organization, Post Office Box 1021, Ramat Yishay 30095, Israel
Tholl, D., Department of Biological Sciences, Virginia Polytechnic Institute and State University, 408 Latham Hall, 220 Ag Quad Lane, Blacksburg, VA 24061, United States
Simon, P.W., Vegetable Crops Research Unit, United States Department of Agriculture, University of Wisconsin, 1575 Linden Drive, Madison, WI 53706, United States
Tadmor, Y., Newe ya'Ar Research Center, Agricultural Research Organization, Post Office Box 1021, Ramat Yishay 30095, Israel
Lewinsohn, E., Newe ya'Ar Research Center, Agricultural Research Organization, Post Office Box 1021, Ramat Yishay 30095, Israel
Ibdah, M., Newe ya'Ar Research Center, Agricultural Research Organization, Post Office Box 1021, Ramat Yishay 30095, Israel

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. © 2013 American Chemical Society.