Heme-containing cytochrome P450 involved in the biosynthesis of xanthophylls. Specific for beta-ring hydroxylation of alpha- and beta-carotene. Has also a low activity toward the epsilon-rings of alpha-carotene. The beta-ring of alpha-carotene is the preferred substrate in planta. Accumulation of alpha-carotene and alpha-cryptoxanthin. Triple mutant cyp97a3, bch1 and bch2 has a highly retarded growth. Alpha-carotene is incorporated into photosystems in lut5 mutants. Belongs to the cytochrome P450 family. Truncated N-terminus.