摘要： 以通过在国际生物信息学网站中获得的、尚未开展分子特征和功能研究的小麦磷转运蛋白基因TaPT2;1为基础,研究了该基因的分子特征和应答外源Pi特征。结果表明,TaPT2;1的cDNA长2 094 bp,编码568个氨基酸,编码蛋白中含有13个保守跨膜域,翻译后蛋白在亚细胞水平上定位于线粒体。在表达特征上,TaPT2;1呈明显的丰磷高表达特征,遭遇低磷逆境后根、叶中的表达水平明显下调;不同器官相比,丰、低磷条件下的该基因表达均为叶片明显高于根系。遗传转化TaPT2;1启动子和报告基因GUS的T₂转基因烟草植株证实,供试基因启动子驱动下游基因的表达,与上述TaPT2;1在不同供磷水平、组织间的表达结果一致。位于TaPT2;1在启动子中的磷素应答特定顺式作用元件PIBS和PHO1,在调控该小麦磷转运蛋白基因对外界磷素水平的应答过程中可能发挥着重要作用。此外,TaPT2;1启动子驱动下游基因在丰磷条件下表达呈光期强-暗期弱典型昼夜节律和随生育进程根、叶中表达不断增强的特征。研究表明,TaPT2;1在介导叶片细胞中Pi由胞质向线粒体的运输中可能发挥重要作用。

关键词: 小麦, 磷转运蛋白基因, 磷水平, 表达, 报告基因

Abstract: Using a wheat phosphate transporter gene TaPT2; 1 that has not been characterized and functionally analyzed as the basis,the molecular characterization and response property of this gene to external Pi were studied in this study. The cDNA length of TaPT2; 1 is 2 094 bp,encoding a 568-aa polypeptide which harbors thirteen conserved membrane-spanning domains. After translation and sorted,TaPT2; 1 targets to the subcellular location of mitochondria. The expression of TaPT2; 1 exhibited a pattern to be strong under sufficient-Pi condition,and to be dramatically down-regulated in leaves and roots when subjected to low-Pi stress. In addition,the expression levels of TaPT2; 1 in leaves were significantly higher than roots under conditions of sufficient and low-Pi. The T 2 transgenic tobacco plants genetically transforming TaPT2; 1 promoter and the reporter gene GUS confirmed the results that obtained in wheat mentioned previously. The expression of GUS under the control of TaPT2; 1 promoter also showed to be higher under sufficient-Pi condition than under low-Pi condition,as well as to be stronger in leaves than in roots under both conditions of sufficient-and low-Pi. The Pi-responsive cis-acting regulatory elements,PIBS and PHO1 that are located at the promoter region of TaPT2; 1,are possibly involved in regulating this wheat phosphate transporter gene to express with a pattern of leaf predominant and induction by Pi sufficience. Furthermore,the downstream gene expression directed by TaPT2; 1 under sufficient-Pi condition displayed a typical circadian rhythm pattern of photo phase-high and dark phase-low and exhibited a obvious pattern of gradually up-regulated along with the growth progression. Our results in this study suggested that TaPT2; 1 play an important role in mediating the trans-portation of Pi from the cellular cytoplasm to the mitochondria.

Key words: Wheat, Phosphate transporter gene, Phosphorus level, Expression, Reporter gene

中图分类号: 

• Q78