A Panax notoginseng phosphate transporter, PnPht1;3, greatly contributes to phosphate and arsenate uptake

Abstract

The crisis of arsenic (As) accumulation in rhizomes threatens the quality and safety of Panax notoginseng(Burk.) F.H. Chen, which is a well-known traditional Chinese herb with a long clinical history. The uptake of arsenate (AsV) could be suppressed by supplying phosphate (Pi), in which Pi transporters play important roles in the uptake of Pi and AsV. Herein, the P. notoginseng Pi transporter-encoding gene PnPht1;3 was identified and characterised under Pi deficiency and AsV exposure. In this study, the open reading frame (ORF) of PnPht1;3 was cloned according to RNA-seq and encoded 545 amino acids. The relative expression levels revealed that PnPht1;3 was significantly upregulated under phosphate deficiency and AsV exposure. Heterologous expression in Saccharomyces cerevisiae MB192 demonstrated that PnPht1;3 performed optimally in complementing the yeast Pi-Transport defect and accumulated more As in the cells. Combined with the subcellular localisation prediction, it was concluded that PnPht1;3 encodes a functional plasma membrane-localised transporter protein that mediates putative high-Affinity Pi/H+ symport activity and enhances the uptake of Pi and AsV. Therefore, a better understanding of the roles of the P. notoginseng Pi transporter could provide new insight for solving As accumulation in medicinal plants.