Catalyzes the C6-oxidation step in brassinosteroids biosynthesis (PubMed:14615594). May convert 6-deoxoteasterone (6-deoxoTE) to 3-dehydro-6-deoxoteasterone (6-deoxo3DT, 6-deoxo3DHT), and teasterone (TE) to 3-dehydroteasterone (3DT, 3-DHT) (PubMed:14615594). Involved in the elongation of leaf sheaths and stems (PubMed:14615594). 6-deoxoteasterone + O2 + reduced [NADPH--hemoprotein reductase] = 3-dehydro-6-deoxoteasterone + H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] Plant hormone biosynthesis; brassinosteroid biosynthesis. Expressed at low levels leaf blades, shoot apex and elongating stem. Down-regulated by brassinolide (BL) in ebisu dwarf (d2) mutant. Plants show abnormalities in growth: inhibition of second internode elongation, shortened leaf sheaths, erect leaves, and deficiency in skotomorphogenesis. Treatment with exogenous brassinolide (BL) rescues the abnormal phenotype. Belongs to the cytochrome P450 family.