CCD1 has broad substrate specificity. It cleaves numerous cyclic and linear all-trans-carotenoids at the C9?C10 and C9'?C10' double bonds. OsCCD1 has three cleavage sites at C9?C10, C7?C8 and C5?C6 double bonds of linear and monocyclic carotenoids (Ilg et al., 2009).