小麦磷转运蛋白基因TaPT4的克隆和表达分析

在富集低磷响应基因的小麦根系cDNA差减杂交文库中,测序后获得1个与大麦磷转运蛋白基因HvPT4高度同源的表达序列标签TaPT4-EST。经BLAST分析获得该EST对应的全长cDNA,将其命名为TaPT4。TaPT4的cDNA全长为1 927bp,编码537个氨基酸残基,编码蛋白含有12个跨膜保守域。系统进化分析表明,TaPT4除与HvPT4具有较高的相似性外,还与呈高亲和特征的黑麦磷转运蛋白基因PT和小麦磷转运蛋白基因PT1高度同源。TaPT4在叶中的表达为组成型,在根中的表达受到低磷诱导;此外,无论在低磷处理还是正常供磷条件下,TaPT4在根中的表达均表现明显的昼夜节律特征,表现为随照光时间延长而表达增高,进入暗期后表达减弱。上述结果表明TaPT4可能是归属于高亲和特征的小麦磷转运蛋白,在增强小麦在低磷逆境下的磷素吸收中发挥着重要作用。

Cloning and molecular characterization analysis of TaPT4,a phosphate transporter gene in wheat(Triticum aestivum L.)

Within a subtractive suppression cDNA library derived from wheat roots that enriched genes induced by low-Pi stress,an expressed sequence tag referred to TaPT4-EST showing high similarity to HvPT4,a barley phosphate transporter(PT) gene,was identified.The full-length cDNA corresponding to this wheat EST was figured out based on BLAST analysis.We designate this wheat gene as TaPT4.The full-length cDNA of TaPT4 is 1927 bp,encoding 537 amino acids that contains twelve conserved transmembrane domains.Phylogenetic analysis revealed that TaPT4 shares high similarities to PT genes from Secale cereale(referred to PT) and wheat(referred to PT1) that belong to high-affinity type,in addition to its homologous HvPT4 mentioned earlier.TaPT4 is constitutively expressed in leaves,while it is induced in roots.Moreover,the expressions of TaPT4 are both shown distinctly diurnal patterns in roots under low-Pi stress condition as well as under normal Pi-supply condition,with high levels during the day time and low levels during the night time.Taken together,as one member of high-affinity PT gene,TaPT4 is suggested to play important roles in taking up of Pi in plants under low-Pi stress condition in wheat.