大豆中介体亚基基因鉴定及表达特性分析

Identification and Expression Profiles of Mediator Subunit Genes in Soybean

中介体复合物在真核生物蛋白编码基因和非编码RNA的转录中非常重要。为了分析大豆中介体亚基的序列特征和基因表达模式,应用BLASTp获取与拟南芥中介体亚基同源的蛋白序列,用Clustal Omega、MAFFT、MEGA等方法进行多序列联配和进化分析,同时应用Me V构建了基因的表达量热图。结果表明:共获得118个基因位点(Locus),186个转录本,在大豆20条染色体上均有分布。Med8的N端具有TBP结构域,Med31的C端具有脯氨酸富集区和假定的核定位信号,Med16的C端有C2-C2型锌指结构域(Zinc-finger motif)。栽培大豆与野生大豆的同源蛋白亲缘关系最近,进化分析符合物种进化规律。大豆不同中介体亚基基因的表达量差异很大,但同一基因在不同组织中的表达差异较小,仅有3个基因在根瘤中特异表达,1个基因在豆荚中特异表达。脱水处理后5个中介体亚基基因表达上调明显,Na Cl处理1和6 h后分别有2和3个中介体亚基基因表达显著上调。这为进一步分析中介体亚基在大豆发育和逆境胁迫中的分子功能奠定基础。

Mediator complex plays important roles in transcriptional regulation of both protein-coding genes and non-coding RNA in eukaryotes. In order to analyze sequence characteristics and expression pattern of soybean mediator subunit genes, homologous of Arabidopsis thaliana- mediator subunits were obtained from phytozome V 9.1 database by BLASTp, multiple sequence alignments and phylogenetic trees were analyzed by Clustal Omega, MAFFT, MEGA 6.0 and other software, gene expression profiles were constructed with MeV V 4.9. The results showed that a total of 186 transcripts （belongs to 118 gene loci） were obtained and distributed on all of the 20 soybean chromosomes.The N.Terminus of Med8 has a TATA-box-binding protein （TBP） domain, the C.Terminus of plant Med31 has a proline rich region and a putative nuclear localization signal （NLS）, and the C.Terminus of Med16 has a C2-C2 zinc finger domain. Subunits of cultivated soybean are closer to wild soybean, which conform to evolution theory. There were great differences in the transcriptional level between different soybean mediator subunit genes in the same tissue, but less difference for the same gene expression in different tissues, expect three genes specifically expressed in root and one in pod Five subunit genes were up-regulated after dehydration treatment, two and three genes after 1 and 6 h of NaCl treatment respectively. This will lay the foundation for further analysis of molecular functions of mediator subunits in soybean development and stress response.