Molecule Characteristic, Expression Of Phosphate Transporter Genes In Wheat And Gene Genetic Transformation

The uptake by the roots and the transportation in cells and tissues of inorganic phosphorus (Pi) were mediated by the phosphate transporters which are located at the cytoplasm membrane. The process of uptake and transportation of Pi is necessary of the energy supply. So far, few studies about of wheat (Triticum aestivum L.) phosphate transporters have been reported. In this study, the molecular characterization, expression patterns of several phosphate transporter genes derived from wheat and its ancestor Triticum boeoticum were analyzed based on modern bioinformatic approach and molecular biological techniques.1. Based on serches of wheat phosphate transporter genes in international bioinformatics website (NCBI), four wheat phosphate transporter genes with uncharacterized, unknown expression patterns and functions were obtained. The GenBank accession numbers were AF488415, AJ830009, AY293827, and AY293828. In this study, they were designated as TaPT1, TaPT2, TaPT3, and TaPT4, respectively.2. The translated amino acids of TaPT1~TaPT4 changed from 467~555, with the morlecular weights of 57.44~60.86 and 11 to 14 conserved transmembrane domains, and protein kinase C activation sites, and casein phosphorylation sites. Therefore, TaPT1~TaPT4 own the conserved structural properties of phosphate transporters in plant species. There were dramatic differences on the expression patterns of the tested phosphate transporter gens. Under normal Pi-supply condition, there were similar transcripts of TaPT1 in roots and leaves, with a pattern that no transcripts detected in roots under low-Pi condition and elevated expression levels with the extension of low-Pi treatment. The expressions of TaPT2 and TaPT3 were shown root specific, also increased in transcripts with the extension of low-Pi treatment. The expression patter of TaPT4 in roots and leaves under various-Pi conditions was shown to be constitutive.3. Using genome walking approach, the promoter region of TaPT2 with 1237 bp length was isolated. The conserved regulatory elements functional on transcriptional regulation, such as TATA box and CAAT box were identified. The Pi-starvation response element PHO-like (GACGTGG, -18 bp) was also figured out in TaPT2 promoter, indicating that this element possibly involved in the low-Pi cue responding of TaPT2.4. Using DNA recombinant technology, the binary cassette of TaPT2-Gus, and series of cassettes in which the reporter gene Gus being driven by the deleted promoter fragments have been constructed. This work would provide the basis for further exploration of the transcriptional regulation of TaPT2 in the future.5. Based on a DNA clone (GenBank accession number: AF488415), a phosphate transporter gene TabPT1 was identified. The molecular characterization, expression pattern were evaluated. It is found that the TabPT1 was the ancestor of TaPT1, the phosphate transporter gene which was former characterized. There were same molecular characterization and expression patterns between TabPT1 and TaPT1. The binary cassettes fused the open reading frame (ORF), the TabPT1 promoter and its series of deleted promoter fragments have been constructed, aiming at further understanding of the transcriptional regulation and function in the future.