Activation of the cytochrome P450 gene, CYP72C1, reduces the levels of active brassinosteroids in vivo
Activation of the cytochrome P450 gene, CYP72C1, reduces the levels of active brassinosteroids in vivo
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DOI：
10.1093/jxb/eri073
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发表时间：
2005-03-01
影响因子：
6.9
通讯作者：
Nagatani, A
中科院分区：
文献类型：
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作者：
Nakamura, M;Satoh, T;Nagatani, A
在昏暗的远红光下筛选用活化载体转化的拟南芥系的库中的短下胚轴突变体，并分离出三个命名为chibi 1 -3（chi）的突变系。在chi突变体中，chi 2占主导地位。无论光照条件如何，chi 2幼苗都很矮。chi 2成熟植株表现出表型特征，如矮化、降低的雄性育性和深绿色、圆形的上位叶，这是油菜素内酯缺失突变体如det 2、cpd和dwf 4的特征。此外，通过向培养基中添加油菜素内酯恢复了下胚轴表型，表明油菜素内酯在该突变体中受到了影响。对chi 2突变体的分子分析表明，CYP 72 C1基因通过插入DNA的增强活性而过表达。用含有35 S启动子和CYP 72 C1基因组DNA之间的嵌合基因的载体转化的野生型植物表现出相似的表型。与形态和生理表型一致，chi 2突变体中活性油菜素类固醇的水平降低。因此，推测CYP 72 C1与BAS 1/CYP 72 B1一起调节植物中的活性油菜素类固醇水平。表达分析表明，野生型CYP 72 C1转录水平增加后，暴露于白色光，虽然这种反应的生理意义仍然模糊。
A pool of Arabidopsis lines transformed with the activation vector was screened for short hypocotyl mutants under dim far-red light, and three mutant lines designated chibi1-3 (chi) were isolated. Among the chi mutants, chi2 was dominant. The chi2 seedlings were short, regardless of the light conditions. The chi2 mature plants exhibited phenotypic features such as dwarfism, reduced male fertility and dark green, rounded epinastic leaves, which are characteristics of brassinosteroid-deficient mutants such as det2, cpd, and dwf4. Furthermore, the hypocotyl phenotype was restored by the addition of brassinolide to the culture medium, suggesting that brassinosteroids had been affected in this mutant. The molecular analysis of the chi2 mutant revealed that the CYP72C1 gene was overexpressed by the enhancing activity of the inserted DNA. Wild-type plants that were transformed with a vector containing a chimeric gene between the 35S promoter and the CYP72C1 genomic DNA exhibited a similar phenotype. Consistent with the morphological and physiological phenotype, the levels of active brassinosteroids were reduced in the chi2 mutant. Hence, CYP72C1, together with BAS1/CYP72B1, is speculated to regulate active brassinosteroid levels in plants. Expression analysis suggested that wild-type CYP72C1 transcript levels increased after exposure to white light, although the physiological significance of such a response remains obscure.