Involved in the biosynthesis of ketocarotenoids which are powerful anti-oxidative molecules (PubMed:16242201, PubMed:21398427, PubMed:22526507). Catalyzes the conversion of beta-carotene to canthaxanthin via echinenone (PubMed:16242201, PubMed:21398427, PubMed:22526507). 2 AH2 + echinenone + 2 O2 = 2 A + canthaxanthin + 3 H2O 2 AH2 + all-trans-beta-carotene + 2 O2 = 2 A + echinenone + 3 H2O Carotenoid biosynthesis. Induced by salt stress.