Molecular characterization and expression analysis of phosphate transporter gene TaPT2-1 in wheat (Triticum aestivum L.)

Abstract

A transcript-derived fragment (TDF) showing up-regulated expression under low Pi stress and being identical to an uncharacterized phosphate transporter gene TaPT2-1 was cloned in wheat. TaPT2-1 was 2075 bp in length and encoded a 568-aa polypeptide. Transmembrane prediction analysis suggested that TaPT2-1 had 13 conserved transmembrane domains. TaPT2-1 shared much higher similarities to other four homologs from Arabidopsis thaliana, Solanum tuberosum, Capsicum frutescens, and Solanum melongena. The expression of TaPT2-1 was root specific and low Pi inducible, suggesting that it plays roles in roots and is involved in the Pi acquisition under Pi-starved condition. The promoter region of TaPT2-1 was cloned based on genome walk analysis. Several types of cis-regulatory elements, such as low Pi responding and tissue specific, were identified in TaPT2-1 promoter. The transgenic tobacco plants with the integrated TaPT2-1 promoter GUS were generated, and GUS histochemical staining analysis in the roots and leaves of the transgenic plants was performed. The results of GUS staining in roots and leaves under various Pi supply conditions were in accordance with the TaPT2-1 transcripts detected based on RT-PCR analysis. Taken together, the distinct expression of low Pi-induced and root-specific TaPT2-1 suggested that it could be used as the potential gene resource on generation of elite crop germplasms with high Pi use efficiency in the future.

Key words： wheat (Triticum aestivum L.), phosphate transporter, expression; cis-regulatory element

Acknowledgements

This research was supported by the National Natural Science Foundation of China (Grant No. 30971773) and the Key Laboratory of Crop Growth Regulation of Hebei Province.

References

1 Chiou T J, Liu H, Harrison M J (2001). The spatial expression patterns of a phosphate transporter (MtPT1) from Medicago truncatula indicate a role in phosphate transport at the root/soil interface. Plant Journal, 25: 281–293

2 Daram P, Brunner S, Rausch C (1999). Pht2;1 encodes a low-affinity phosphate transporter from Arabidopsis.Plant Cell, 11: 2153–2166

3 Franco-Zorrilla J M, González E, Bustos R (2004). The transcriptional control of plant response phosphate limitation. Journal of Experimental Botany, 55(396): 285–293

4 Gu J T, Bao J X, Wang X Y, Guo C J, Li X J, Lu W J, Xiao K (2009). Investigation of differential expressed genes responding to deficient-Pi in wheat as revealed by cDNA-AFLP analysis. Acta Agronomica Sinica, 35(9): 1597–1605

5 Guo L, Long S, Zhao F, Bao J, Guo C, Xiao Kai (2008). Comparison and biochemical evaluation criteria for phosphorus efficiency in wheat. Journal of Plant Genetic Resources, 9(4): 506–510 (in Chinese)

6 Guo L, Zhao Y, Zhang S, Zhang H, Xiao K (2009). Improvement of organic phosphate acquisition in transgenic tobacco plants by overexpression of a soybean phytase gene Sphy1. Frontiers of Agriculture in China, 3(3): 259–265

7 Hammond J P, Bennett M J, Bowen H C (2003). Changes in genes expression in Arabidopsis shoots during phosphate starvation and the potential for developing smart plants. Plant Physiology, 132: 1–19

8 Jefferson R A, Kavanagh T A, Bevan M W (1987). GUS fusions: ß-glucoronidase as a sensitive and versatile gene fusion marker in higher plants. EMBO Journal, 6: 3901–3907

9 Karthikeyan A S, Varadarajan D K, Mukatira U T, D’Urzo M P, Damsz B, Raghothama K G (2002). Regulated expression of Arabidopsis phosphate transporters. Plant Physiology,130: 221–233

10 Liu C, Muchhal U S, Uthappa M (1998). Tomato phosphate transporter genes are differentially regulated in plant tissues by phosphorus. Plant Physiology, 116(1): 91–99

11 Liu H,Trieu A T, Blaylock L A (1998). Cloning and characterization of two phosphate transporters from Medicago truncatula roots: regulation in response to phosphate and to colonization by arbuscular mycorrhizal (AM) fungi. Molecular Plant-Microbe Interactions, 11(1): 14–22

12 Liu J, Versaw W K, Pumplin N (2008). Closely related members of the Medicago truncatula PHT1 phosphate transporter gene family encode phosphate transporters with distinct biochemical activities. Journal of Biological Chemistry, 283: 24673–24681

13 Mitsukawa N, Okumura S, Shirano Y, Sato S, Kato T, Harashima S, Shibata D (1997). Overexpression of an Arabidopsis thaliana high-affinity phosphate transporter gene in tobacco cultured cells enhances cell growth under phosphate-limited conditions.Proceedings of the National Academy of Sciences, USA, 94: 7098–7102

14 Muchhal U S, Pardo J M, Raghothama K G (1996). Phosphate transporters from the higher plant Arabidopsis thaliana.Proceedings of the National Academy of Sciences, USA, 96: 5868–5872

15 Mudge S R, Rae A L, Diatloff E, Smith F W (2002). Expression analysis suggests novel roles for members of the Pht1 family of phosphate transporters in Arabidopsis. Plant Journal, 31: 341–353

16 Okumura S, Mitsukawa N, Shirano Y, Shibata D (1998). Phosphate transporter gene family of Arabidopsis thaliana. DNA Research, 5: 261–269

17 Rae A L, Cybinski D H, Jarmey J M, Smith F W (2003). Characterization of two phosphate transporters from barley; evidence for diverse function and kinetic properties among members of the Pht1 family. Plant Molecular Biology, 53: 27–36

18 Raghothama K (1999). Phosphate acquisition. Annual Review of Plant Physiology and Plant Molecular Biology, 50: 665–693

19 Rausch C, Bucher M (2002). Molecular mechanisms of phosphate transport in plants. Planta, 216: 23–37

20 Rubio V, Linhares F, Solano R, Martin A C, Iglesias J, Leyva A, Paz-Ares J (2001). A conserved MYB transcription factor involved in phosphate starvation signaling both in vascular plants and in unicellular algae. Genes Development, 15: 2122–2133

21 Schünmann P H D, Richardson A E, Smith F W, Delhaize E (2004). Characterization of promoter expression patterns derived from the Pht1 phosphate transporter genes of barley (Hordeum vulgare L.). Journal of Experimental Botany, 55: 855–865

22 Seo H M, Jung Y, Song S (2008). Increased expression of OsPT1, a high-affinity phosphate transporter, enhances phosphate acquisition in rice. Biotechnology Letters, 30: 1833–1838

23 Smith F W, Ealing P M, Dong B, Delhaize E (1997). The cloning of two Arabidopsisgenes belonging to a phosphate transporter family. Plant Journal, 11: 83–92

24 Smith F W, Rae A L, Hawkesford M J (2000). Molecular mechanisms of phosphate and sulphate transport in plants. Biochimica et Biophysica Acta, 1465: 236–245

25 Vance C P, Uhde-Stone C, Allan D L (2003). Phosphorus acquisition and use: critical adaptations by plants for securing a non-renewable resource. New Phytologist, 157: 423–447