Zeaxanthin epoxidase that plays an important role in the xanthophyll cycle and abscisic acid (ABA) biosynthesis. Converts zeaxanthin into antheraxanthin and subsequently violaxanthin. Required for resistance to osmotic and drought stresses, seed development and dormancy. all-trans-zeaxanthin + 4 H(+) + 2 O2 + 4 reduced [2Fe-2S]-[ferredoxin] = all-trans-violaxanthin + 2 H2O + 4 oxidized [2Fe-2S]-[ferredoxin] Plant hormone biosynthesis; abscisate biosynthesis. Expressed in young microspores. By cold in microspores. Accumulation of endogenous zeaxanthin and reduced level of ABA. Wilty phenotype, increased water loss and premature seed germination.