Has a 11,12(11',12') 9-cis epoxycarotenoid cleavage activity. Catalyzes the first step of abscisic-acid biosynthesis from carotenoids. a 9-cis-epoxycarotenoid + O2 = 2-cis,4-trans-xanthoxin + a 12'-apo-carotenal 9-cis-violaxanthin + O2 = (3S,5R,6S)-5,6-epoxy-3-hydroxy-5,6-dihydro-12'-apo-beta-caroten-12'-al + 2-cis,4-trans-xanthoxin 9'-cis-neoxanthin + O2 = (3S,5R,6R)-3,5-dihydroxy-6,7-didehydro-5,6-dihydro-12'-apo-beta-caroten-12'-al + 2-cis,4-trans-xanthoxin Binds 1 Fe(2+) ion per subunit. Partially bound to the thylakoid. Very low in all tissues. Expressed at the point of organ attachment and the abscission zones in the plant. Low induction by drought stress. Belongs to the carotenoid oxygenase family.