Cloning and Characterisation of a novel phosphate transporter gene EcPT1 from Eichhornia crassipes

Eichhornia crassipes (Mart.) Solms can absorb nitrogen and phosphorus efficiently from water. Cloning the phosphate transporter 1 from E. crassipes (EcPHT1) and studying its characteristics can help to explain the molecular mechanism of absorption and transportation of inorganic phosphate (Pi) in E. crassipes and develop new genetic resources for phosphate transport to aid genetic breeding of crops with increased phosphate use efficiency. In this paper, we have used RACE method to clone the EcPT1 with 1572 bps which encoded a polypeptide of 523 amino acids and contained 11 transmembrane regions which was the typical structure of plant PHT1. The phylogenetic analysis also showed EcPT1 was closely related to other plant PHT1s. Quantitative real-time RT-PCR (qRT-PCR) showed that the EcPT1 expression in roots was up-regulated under low phosphorus stress . Moreover the EcPT1 expression in leaves was suppressed after E. crassipes was transferred to sufficient Pi from deficient Pi. Yeast functional complementation tests showed that the EcPT1 could complement the phosphate transport function of the Pi deficient yeast PHO84 in 175 mu M Pi and make it grow best in pH = 5 or 6. All these results indicated that EcPT1 might be a phosphate transporter gene. Its expression was different in different tissues.