Cleaves a variety of carotenoids at the 9-10 and 9'-10' double bonds. Probably not involved in abscisic acid biosynthesis. all-trans-zeaxanthin + 2 O2 = 2 (3R)-hydroxy-beta-ionone + 4,9-dimethyldodeca-2,4,6,8,10-pentaenedial Binds 1 Fe(2+) ion per subunit. Homodimer. Constitutively expressed in embryos. Belongs to the carotenoid oxygenase family.