烟草磷转运蛋白基因NtPHT2;1的克隆和表达分析

植物对磷酸盐的吸收与利用主要依靠磷转运蛋白，其中PHT2家族编码的低亲和磷转运蛋白主要负责植物在正常供磷条件下磷酸盐的吸收、转运与再利用。为了探究低亲和磷转运蛋白基因NtPHT2;1在烟草转运磷酸盐中的作用和表达模式，本研究以普通烟草K326的cDNA为模板，克隆得到NtPHT2;1，对该基因进行生物信息学分析和蛋白质的亚细胞定位，并通过荧光定量PCR技术对该基因在低磷等非生物胁迫下的基因表达模式进行分析。结果表明：（1）NtPHT2;1基因的全长为1 764 bp，编码587个氨基酸。（2）亚细胞定位结果表明，NtPHT2;1蛋白定位于叶绿体上。（3）同源性比对发现，NtPHT2;1蛋白与辣椒CaPHT2;1蛋白的同源性最高达到91.00%。（4）启动子分析表明，NtPHT2;1启动子含有参与调控植物衰老、逆境胁迫相关的顺式作用元件。（5）组织表达模式分析表明，NtPHT2;1在叶片中的表达量最高，新叶中的表达量比老叶中的高；在低磷诱导条件下，该基因的表达量与正常条件相比差异不显著。（6）不同非生物胁迫下的表达模式表明，在盐胁迫和干旱胁迫下，该基因的表达量显著降低。研究认为，NtPHT2;1基因主要是负责烟株正常生长发育条件下磷酸盐的转运与利用。

Cloning and expression analysis of phosphorus transporter gene NtPHT2;1 in Nicotiana tabacum

The absorption and utilization of phosphate by plants mainly depend on phosphorus transporters, among which the low-affinity phosphorus transporters encoded by the PHT2 family are mainly responsible for the absorption, transport and reuse of phosphate by plants under normal phosphorus supply conditions. In order to explore the role and expression mode of low-affinity phosphorus transporter gene NtPHT2;1 in tobacco phosphate transport, this study cloned NtPHT2;1 using the cDNA of common tobacco K326 as a template, and conducted bioinformatics analysis of the gene and subcellular localization of the protein. The expression patterns of this gene under abiotic stress such as low phosphorus were analyzed by fluorescence quantitative PCR. The results showed that: (1) The total length of NtPHT2;1 gene is 1 764 bp and encodes 587 amino acids. (2) The results of subcellular localization showed that NtPHT2;1 protein was localized on chloroplasts. (3) Homology analysis showed that the homology between NtPHT2;1 protein and CaPHT2;1 protein reached 91.00%. (4) Promoter analysis showed that NtPHT2;1 promoter contains cis-acting elements involved in the regulation of plant aging and stress. (5) Tissue expression pattern analysis showed that the expression level of NtPHT2;1 was the highest in leaves, and the expression level in new leaves was higher than that in old leaves. There was no significant difference in the expression of this gene under low phosphorus induction compared with normal conditions. (6) The expression patterns under different abiotic stresses showed that the expression of this gene decreased significantly under salt stress and drought stress. It is concluded that NtPHT2;1 gene is mainly responsible for phosphate transport and utilization under normal growth and development of tobacco plants.