Miao Jun, Sun Jinghan, Liu Dongcheng, Li Bin, Zhang Aimin, Li Zhensheng, Tong Yiping
The State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
J Genet Genomics. 2009 Aug;36(8):455-66. doi: 10.1016/S1673-8527(08)60135-6.
TaPHT1.2 is a functional, root predominantly expressed and low phosphate (Pi) inducible high-affinity Pi transporter in wheat, which is more abundant in the roots of P-efficient wheat genotypes (e.g., Xiaoyan 54) than in P-inefficient genotypes (e.g., Jing 411) under both Pi-deficient and Pi-sufficient conditions. To characterize TaPHT1.2 further, we genetically mapped a TaPHT1.2 transporter, TaPHT1.2-D1, on the long arm of chromosome 4D using a recombinant inbred line population derived from Xiaoyan 54 and Jing 411, and isolated a1,302 bp fragment of the TaPHT1.2-D1 promoter (PrTaPHT1.2-D1) from Xiaoyan 54. TaPHT1.2-D1 shows collinearity with OsPHT1.2 that has previously been reported to mediate the translocation of Pi from roots to shoots. PrTaPHT1.2-D contains a number of Pi-starvation responsive elements, including P1BS, WRKY-binding W-box, and helix-loop-helix-binding elements. PrTaPHT1.2-D1 was then used to drive expression of beta-glucuronidase (GUS) reporter gene in Arabidopsis through Agrobacterium-mediated transformation. Histochemical analysis of transgenic Arabidopsis plants showed that the reporter gene was specifically induced by Pi-starvation and predominantly expressed in the roots. As there is only one SNP between the TaPHT1.2-D1 promoters of Xiaoyan 54 and Jing 411, and this SNP does not exist within the Pi-starvation responsive elements, the differential expression of TaPHT1.2 in Xiaoyan 54 and Jing 411 may not be caused by this SNP.
TaPHT1.2是一种功能性的、主要在根中表达且受低磷（Pi）诱导的小麦高亲和力Pi转运蛋白，在缺磷和供磷充足条件下，它在磷高效小麦基因型（如小偃54）根中的含量比磷低效基因型（如京411）根中的含量更高。为了进一步表征TaPHT1.2，我们利用从小偃54和京411衍生的重组自交系群体，在4D染色体长臂上对TaPHT1.2转运蛋白TaPHT1.2-D1进行了遗传定位，并从小偃54中分离出TaPHT1.2-D1启动子（PrTaPHT1.2-D1）的一个1302 bp片段。TaPHT1.2-D1与之前报道的介导Pi从根向地上部转运的OsPHT1.2具有共线性。PrTaPHT1.2-D含有许多磷饥饿响应元件，包括P1BS、WRKY结合W盒和螺旋-环-螺旋结合元件。然后通过农杆菌介导的转化，利用PrTaPHT1.2-D1驱动拟南芥中β-葡萄糖醛酸酶（GUS）报告基因的表达。转基因拟南芥植株的组织化学分析表明，报告基因在磷饥饿条件下被特异性诱导，且主要在根中表达。由于小偃54和京411的TaPHT1.2-D1启动子之间只有一个单核苷酸多态性（SNP），且该SNP不存在于磷饥饿响应元件内，因此TaPHT1.2在小偃54和京411中的差异表达可能不是由该SNP引起的。
