Insights into the formation of carlactone from in‐depth analysis of theCCD8‐catalyzed reactions

Strigolactones are a new class of phytohormones synthesized from carotenoids via carlactone. The complex structure of carlactone is not easily deducible from its precursor, a cis ‐configured β‐carotene cleavage product, and is thus formed via a poorly understood series of reactions and molecular rearrangements, all catalyzed by only one enzyme, the carotenoid cleavage dioxygenase 8 ( CCD 8). Moreover, the reactions leading to carlactone are expected to form a second, yet unidentified product. In this study, we used 13 C and 18 O‐labeling to shed light on the reactions catalyzed by CCD 8. The characterization of the resulting carlactone by LC ‐ MS and NMR , and the identification of the assumed, less accessible second product allowed us to formulate a minimal reaction mechanism for carlactone generation.