Mathur J, Molnár G, Fujioka S, Takatsuto S, Sakurai A, Yokota T, Adam G, Voigt B, Nagy F, Maas C, Schell J, Koncz C, Szekeres M
Max Planck-Institut für Züchtungsforschung, Köln, Germany.
Plant J. 1998 Jun;14(5):593-602. doi: 10.1046/j.1365-313x.1998.00158.x.
The Arabidopsis CPD gene encodes a cytochrome P450 steroid side-chain hydroxylase (CYP90) that plays an essential role in the biosynthesis of the plant hormone brassinolide. Expression of the CPD gene is confined to cotyledons and leaf primordia in etiolated seedlings and detectable in the adaxial parenchyma of expanding leaves in light-grown plants. Transcription of the CPD gene is not affected by the plant growth factors auxin, ethylene, gibberellin, cytokinin, jasmonic acid and salicylic acid, but is specifically down-regulated by brassinolide in both dark and light. Steady-state mRNA levels of a CPD promoter-driven uidA reporter gene correlate with the expression of resident CPD gene in transgenic plants. Intermediates of the early and late C-6 oxidation pathways of brassinolide, carrying C-22 and C-23 side-chain hydroxyls, efficiently inhibit the activity of the CPD promoter. Repression of CPD transcription by brassinosteroids is sensitive to the protein synthesis inhibitor cycloheximide, indicating a requirement for de novo synthesis of a regulatory factor.
拟南芥CPD基因编码一种细胞色素P450类固醇侧链羟化酶（CYP90），它在植物激素油菜素内酯的生物合成中起关键作用。CPD基因的表达局限于黄化幼苗的子叶和叶原基，在光照生长的植物中，可在正在伸展叶片的近轴薄壁组织中检测到。CPD基因的转录不受植物生长因子生长素、乙烯、赤霉素、细胞分裂素、茉莉酸和水杨酸的影响，但在黑暗和光照条件下均受到油菜素内酯的特异性下调。在转基因植物中，由CPD启动子驱动的uidA报告基因的稳态mRNA水平与内源性CPD基因的表达相关。携带C-22和C-23侧链羟基的油菜素内酯早期和晚期C-6氧化途径的中间体，能有效抑制CPD启动子的活性。油菜素类固醇对CPD转录的抑制作用对蛋白质合成抑制剂环己酰亚胺敏感，这表明需要从头合成一种调节因子。
