Catalyzes the C6-oxidation step in brassinosteroids biosynthesis (PubMed:11402205, PubMed:12529536). Converts 6-deoxocastasterone (6-deoxoCS) to castasterone (CS). May also convert 6-deoxoteasterone (6-deoxoTE) to teasterone (TE), 3-dehydro-6-deoxoteasterone (6-deoxo3DT, 6-deoxo-3-DHT) to 3-dehydroteasterone (3DT, 3-DHT), and 6-deoxotyphasterol (6-deoxoTY) to typhasterol (TY) (PubMed:11402205, PubMed:12529536). Required for the initiation of female gametogenesis (megagametogenesis) (PubMed:21364326). 6-deoxoteasterone + O2 + reduced [NADPH--hemoprotein reductase] = 6alpha-hydroxyteasterone + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] 6alpha-hydroxytyphasterol + O2 + reduced [NADPH--hemoprotein reductase] = H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] + teasterone 3-dehydro-6-deoxoteasterone + O2 + reduced [NADPH--hemoprotein reductase] = 3-dehydro-6alpha-hydroxyteasterone + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] 3-dehydro-6alpha-hydroxyteasterone + O2 + reduced [NADPH--hemoprotein reductase] = 3-dehydroteasterone + H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] 6-deoxotyphasterol + O2 + reduced [NADPH--hemoprotein reductase] = 6alpha-hydroxytyphasterol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] 6alpha-hydroxytyphasterol + O2 + reduced [NADPH--hemoprotein reductase] = H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] + typhasterol 6-deoxocastasterone + O2 + reduced [NADPH--hemoprotein reductase] = 6alpha-hydroxycastasterone + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] 6alpha-hydroxycastasterone + O2 + reduced [NADPH--hemoprotein reductase] = castasterone + H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] 3-dehydro-6-deoxoteasterone + 2 O2 + 2 reduced [NADPH--hemoprotein reductase] = 3-dehydroteasterone + 2 H(+) + 3 H2O + 2 oxidized [NADPH--hemoprotein reductase] 6-deoxocastasterone + 2 O2 + 2 reduced [NADPH--hemoprotein reductase] = castasterone + 2 H(+) + 3 H2O + 2 oxidized [NADPH--hemoprotein reductase] 6-deoxoteasterone + 2 O2 + 2 reduced [NADPH--hemoprotein reductase] = 2 H(+) + 3 H2O + 2 oxidized [NADPH--hemoprotein reductase] + teasterone 6-deoxotyphasterol + 2 O2 + 2 reduced [NADPH--hemoprotein reductase] = 2 H(+) + 3 H2O + 2 oxidized [NADPH--hemoprotein reductase] + typhasterol Plant hormone biosynthesis; brassinosteroid biosynthesis. Mainly expressed in apical shoots, hypocotyls, siliques and roots (PubMed:12529536, PubMed:32333772). Also present in the female gametophyte (PubMed:21364326). In the female gametophyte, accumulates in ovules and its neighboring sporophytic cells. Repressed by brassinolide (BL) treatment (PubMed:12427998). Induced rapidly and transiently in seedlings hooks but fades out of hypocotyls after exposure to light (PubMed:32333772). No obvious morphological alteration during vegetative or floral development, but semi-sterile phenotype with several female gametophytes arrested before the first nuclear mitotic division of the haploid functional megaspore. Belongs to the cytochrome P450 family.