水稻NHX1基因启动子和C末端的调控功能研究

为了解水稻Na+/H+逆向转运蛋白(OsNHX1)在植物应答非生物胁迫中的分子调控机制,采用RT-PCR方法克隆OsNHX1基因上游2 000bp的启动子序列,并通过基因枪轰击瞬时转化洋葱表皮细胞,检测不同非生物胁迫下启动子的活性和表达模式;同时,分别克隆全长和C末端缺失的OsNHX1基因,通过花序浸染法转化拟南芥,研究OsNHX1基因及其C末端的功能。结果显示:OsNHX1启动子受逆境胁迫诱导,在盐、干旱、脱落酸胁迫处理下GUS表达活性明显升高;过表达OsNHX1的转基因拟南芥中,种子萌发率、根长、丙二醛含量和相对含水量的测定结果均显示其胁迫耐受性得到改善,但过表达OsNHX1C末端缺失基因对转基因植株的胁迫耐受性无明显影响。研究表明,Na+/H+逆向转运蛋白有助于提高植物耐盐性,且其C末端区域对该转运蛋白活性的发挥具有关键作用。

Regulation of Rice (Oryza sativa) NHX1 Gene:Role of Its Promoter and C terminal

In order to understand the molecular regulative mechanism of rice(Oryza sativa) Na+/H+ antiporter(OsNHX1) in plant response to abiotic stresses,a 2 000 bp upstream region of OsNHX1 gene was cloned and transformed into onion epidermal cells by particle bombardment to detect the promoter’s activity and expression pattern under various abiotic stresses.Full length OsNHX1 and C-terminal truncated OsNHX1(OsNHX1dC) gene were also cloned and transformed into Arabidopsis thaliana separately by floral dipping method to investigate the function of OsNHX1 C-terminal.The results showed that the OsNHX1 promoter was induced by abiotic stresses and the GUS activity was enhanced significantly under salt,drought and ABA treatments.The assays of germination rate,root length,MDA and relative water content(RWC) exhibited that over-expression of OsNHX1 improved the salt and drought tolerance of transgenic plants,whereas no distinguishing difference was found between the OsNHX1dC transgenic and wild-type plants,suggesting that OsNHX1 contributed to an improved tolerance to salt stress in plants and the C-terminal tail was critical for the activity of Na+/H+ antiporter.