A novel cytochrome P450 is implicated in brassinosteroid biosynthesis via the characterization of a rice dwarf mutant, dwarf11, with reduced seed length
A novel cytochrome P450 is implicated in brassinosteroid biosynthesis via the characterization of a rice dwarf mutant, dwarf11, with reduced seed length
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DOI：
10.1105/tpc.104.024950
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发表时间：
2005-03-01
期刊：
影响因子：
11.6
通讯作者：
Iwasaki, Y
中科院分区：
文献类型：
--
作者：
Tanabe, S;Ashikari, M;Iwasaki, Y
我们已经描述了一个水稻矮秆突变体，dwarf 11（d11），种子长度减少。为了了解种子长度调节的机制，通过基于图位的克隆方法分离D11基因。发现该基因编码一种新的细胞色素P450（CYP 724 B1），该基因与油菜素类固醇（BR）生物合成相关酶具有同源性。d 11突变体的矮化表型通过施用油菜素（BL）而恢复。与野生型植物相比，异常的D11 mRNA积累在更高的水平在d11突变体和BL处理显着减少，这意味着该基因是由BL反馈调节。由于组织特异性和植物中BR积累的复杂控制，在d11突变体中11313合成中的缺陷步骤的精确测定被证明是困难的。然而，6-deoxotyphasterol（6-DeoxotTY）和typhasterol（TY），但不是任何上游的中间体之前，这些化合物，有效地恢复BR反应在d11突变体在椎板关节弯曲试验。多条证据共同表明D11/CYP 724 BI基因在BR合成中起作用，并可能参与水稻BR生物合成网络中6-DeoxoTY和TY的供应。
We have characterized a rice (Oryza sativa) dwarf mutant, dwarf11 (d11), that bears seeds of reduced length. To understand the mechanism by which seed length is regulated, the D11 gene was isolated by a map-based cloning method. The gene was found to encode a novel cytochrome P450 (CYP724B1), which showed homology to enzymes involved in brassinosteroid (BR) biosynthesis. The dwarf phenotype of d11 mutants was restored by the application of the brassinolide (BL). Compared with wild-type plants, the aberrant D11 mRNA accumulated at higher levels in d11 mutants and was dramatically reduced by treatment with BL, implying that the gene is feedback-regulated by BL. Precise determination of the defective step(s) in 11313 synthesis in d11 mutants proved intractable because of tissue specificity and the complex control of BR accumulation in plants. However, 6-deoxotyphasterol (6-DeoxoTY) and typhasterol (TY), but not any upstream intermediates before these compounds, effectively restored BR response in d11 mutants in a lamina joint bending assay. Multiple lines of evidence together suggest that the D11/CYP724BI gene plays a role in BR synthesis and may be involved in the supply of 6-DeoxoTY and TY in the BR biosynthesis network in rice.