Mediator is a large, modular protein complex, and plays the important roles in regulating transcription in eukaryotes. Growth and development of a plant are controlled by programmed expression of suits of genes at the appropriate time, tissue and abundance. Although mediator has been studied rapidly in recent years in A rabidopsis thaliana, but the expression profiling patterns of mediator subunits remains largely unknown. In this study, using the coding sequences (CDS) of mediator subunits in Arabidopsis thaliana as searching sequences, a total of 24 mediator subunits CDS were found in rice (Oryza saliva) by BLAST with nucleonic acid data base of NCBI. Medl9 had two copies, all the rest had only one copy in rice among the obtained 24 genes. The expression profiles of 23 subunit genes based on 59 Affymetrix GeneChip samples of japonica rice were obtained by clustering method. In these subunit genes, 0sMedl2 had the highest specificity expression, the fellowing was OsMedll, all the rest 21 genes had differential expression even close to constitutive expression. Analysis of OsMed8 promoter activity by GUS expression showed that OsMed8 highly expressed in meristems, early stages of vegetative and reproductive development, which consistented with the expression profile of OsMedS in clustering analysis. Results of subcellular locations of mediator subunits in Nicotiana benthamiana leaves indicated that OsMed6 was localized in nucleus, and OsMed8 was localized in both the nucleus and the plasma membrane. The results of the expression profiling patterns and subcellular locations of mediator subunits can provide useful informations for studying of their biological roles in rice.%中介体是一种大分子蛋白复合物,在真核生物的转录调控中发挥重要的作用.基因的时空表达控制着植物的生长和发育.虽然近年来拟南芥芥(A rabidopsis thaliana)中介体亚基的功能研究进展迅速,但对其基因的时空表达信息知之甚少.为研究水稻(Oryza sativa)中介体亚基基因的表达模式,以拟南芥中介体亚基基因为查询序列,在NCBI核酸数据库上进行搜索,共获得24个水稻中介体亚基基因,其中除了Med19存在两个拷贝以外,其余22个亚基基因均为单拷贝.利用水稻21个组织共59个样本的芯片数据,对23个中介体亚基基因的表达数据进行聚类,结果表明,OsMed12的表达组织特异性最强,其次为OsMed11,其他21个亚基基因表达无明显规律,较接近组成型表达.以GUS为报告基因的OsMed8启动子活性分析结果与其表达谱结果一致,可以看出在植株的分生组织、营养生长早期和生殖生长初期表达较强.亚细胞定位结果显示,OsMed6被定位在细胞核中;OsMed8定位在细胞核和细胞质膜中.本研究获得了水稻中介体基因的表达模式和蛋白亚细胞定位的重要的数据,对于进一步研究水稻中介体亚基的功能提供了很有价值的参考信息.
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