Cloning, Expression Of A Phosphate Transporter Gene (ZjPT2-1) From Ziziphus Jujuba Mill. And Its Functional Analysis Under Phytoplasma Stress

Phosphate Transporters (PT) play important roles on regulation of acquisition and utilization of Pi in plants. It is a family of multifunctional protein. Based on the homology comparison, PTs are distributed into 3 classes in plant. Pht2 mainly expressed in green tissues and took part in the process of Pi transformation in leaves. A Phosphate Transporter gene(ZjPT2-1, KC479797) of Ziziphus jujuba Mill. was firstly isolated by homologous sequence method. The related function under phytoplasma stress was also studied by relative RT-PCR in this paper. The main results were as follows:1 The Phosphate Transporter gene of Ziziphus jujuba Mill. (ZjPT2-1, KC479797) was firstly isolated by homologous sequence method. The 1704bp included a complete open reading frame which encoded a polypeptide of 567 amino acids.2 Based on bioinformatics analysis, the ZjPT2-1 gene belonged to a Pht2 family. Sequence alignment showed that ZjPT2-1 was highly homologous to the PT2 from other species,98%,92%,79%,79%,79%,78%,78%,76% homologus to Triticum aestivum (AY293827), Brachypodiumn distachyon (XM00357522), Populus trichocarpa (XM002314562), Fragaria vescra subsp. Vesca (XM004309931), Medicago truncatual (XM003628895) Vitis vinifera (XM002271840), Glycin max (XM003530579), Arabidopsis thaliana (NM113565), respectively. The predict-protein is characterized by the molecular weight of 58.8kDa, the isoelectric point of 9.67. The tertiary structure prediction shows that a helix of ZjPT2-1 protein accounted for 58.73%, which is whole a protein (the a helix proportion is greater than 45%), it is a transmembrane protein.3 Prokaryotic expression of ZjPT2-1 was carried out, and a large quantity of the fusion protein of 58kDa was detected in bacterium precipitation.4 After Light and dark treatments, ZjPT2-1 gene expression in light condition was higher than in dark. So light could induce the expression of ZjPT2-1 gene.5 The results of relative RT-PCR showed that ZjPT2-1 gene expression was significantly affected by the infection of JWB phytoplasma. The ZjPT2-1 gene expression was down-regulated in resistant cultivar’Xingguang’ and up-regulated in sensitive cultivar ’Pozao’.