紫萍磷转运蛋白1;1 cDNA序列的克隆及表达模式

紫萍Spirodela polyrrhiza是一种在生物质资源开发利用和水体生物修复中广泛使用的漂浮植物。随着水体富营养化日益严重，紫萍在水面随处可见。有文献报道紫萍对水体中的氮和磷有良好的净化作用。为了深入研究紫萍对水体中无机磷的吸收和转运，以紫萍为材料提取RNA反转录为cDNA，以此为模板，扩增得到1条特异性片段，其开放读码框 (ORF) 全长序列为1 620 bp，编码539个氨基酸，命名为SpPHT1;1，在GenBank中登录号为MN720003。生物信息学分析表明，SpPHT1;1没有内含子，编码的蛋白是一种稳定的、疏水的、具有11个跨膜结构域的蛋白，其结构具有主要协助转运蛋白超家族 (Major facilitator superfamily，MFS) 保守的结构域，聚类分析显示紫萍SpPHT1;1与玉米ZmPHT2和高粱SbPHT1-8有较近的亲缘关系，推测其属于植物磷转运蛋白家族PHT1成员。正常磷条件，SpPHT1;1在紫萍叶中的表达明显多于根；低磷条件促进该基因的表达，相对表达量在紫萍根和叶生长48 h时均达到峰值；丰磷条件会抑制基因表达，说明SpPHT1;1的表达会受到外界磷浓度的影响。研究结果有助于紫萍磷转运蛋白基因功能的进一步深入研究，为紫萍的进一步开发和利用提供理论依据。

Cloning and expression pattern of phosphate transporter 1;1 cDNA sequence from Spirodela polyrrhiza

Spirodela polyrrhiza is a floating plant widely used in biomass utilization and eutrophication phytoremediation. It becomes a common aquatic plant everywhere with the increasingly serious eutrophication. It has been reported that S. polyrrhiza has a good effect on the remediation of eutrophication water. In order to study the absorption and transportation of phosphorus in S. polyrrhiza, we extracted RNA from S. polyrrhiza and then reverse transcribed it into cDNA, which was used as a template to amplify a specific fragment. The full-length sequence of the open reading frame (ORF) was 1 620 bp, encoding 539 amino acids, named SpPHT1;1, and the accession number in GenBank was MN720003. Bioinformatical analysis showed that SpPHT1;1 had no intron. The protein it encoded was a stable, hydrophobic protein with 11 transmembrane domains. SpPHT1;1 structure was similar to that of major facilitator superfamily (MFS) superfamily members. The cluster analysis showed that SpPHT1;1 was closely related to ZMPHT2 in maize and SBPHT1-8 in sorghum. So, it might belong to plant PHT1 family. The expression of SpPHT1;1 in leaf was significantly more than that of root under normal phosphorus condition. Low phosphorus condition could promote gene expression, and the relative expression level of SpPHT1;1 arrived at the peak at 48 h both in root and leaf. High phosphorus condition could inhibit gene expression. These results indicated that SpPHT1;1 expression would be affected by external phosphorus concentration. The results of this study are helpful for further research on the function of phosphate transporter. It also can provide theoretical basis for further development and utilization of S. polyrrhiza.